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Zoonomia/I.XXXIII

SECT. XXXIII.

DISEASES OF SENSATION.

 * I. 1. Motions excited by sensation. Digestion. Generation. Pleasure of existence. Hypochondriacism. 2. Pain introduced. Sensitive fevers of two kinds. 3. Two sensorial powers exerted in sensitive fevers. Size of the blood. Nervous fevers distinguished from putrid ones. The septic and antiseptic theory. 4. Two kinds of delirium. 5. Other animals are less liable to delirium, cannot receive our contagious diseases, and are less liable to madness. II. 1. Sensitive motions generated. 2. Inflammation explained. 3. Its remote causes from excess of irritation, or of irritability, not from those pains which are owing to defect of irritation. New vessels produced, and much heat. 4. Purulent matter secreted. 5. Contagion explained. 6. Received but once. 7. If common matter be contagious? 8. Why some contagions are received but once. 9. Why others may be received frequently. Contagions of small-pox and measles do not act at the same times. Two cases of such patients. 10. The blood from patients in the small-pox will not infect others. Cases of children thus inoculated. The variolous contagion is not received into the blood. It acts by sensitive association between the stomach and skin. III. 1. Absorption of solids and fluids. 2. Art of healing ulcers. 3. Mortification attended with less pain in weak people.

I. 1 . As many motions of the body are excited and continued by irritations, so others require, either conjunctly with these, or separately, the pleasurable or painful sensations, for the purpose of producing them with due energy. Amongst these the business of digestion supplies us with an instance: if the food, which we swallow, is not attended with agreeable sensation, it digests less perfectly; and if very disagreeable sensation accompanies it, such as a nauseous idea, or very disgustful taste, the digestion becomes impeded; or retrograde motions of the stomach and œsophagus succeed, and the food is ejected.

The business of generation depends so much on agreeable sensation, that, where the object is disgustful, neither voluntary exertion nor irritation can effect the purpose; which is also liable to be interrupted by the pain of fear or bashfulness.

Besides the pleasure, which attends the irritations produced by the objects of lust and hunger, there seems to be a sum of pleasurable affection accompanying the various secretions of the numerous glands, which constitute the pleasure of life, in contradistinction to the tedium vitæ. This quantity or sum of pleasurable affection, seems to contribute to the due or energetic performance of the whole moveable system, as well that of the heart and arteries, as of digestion and of absorption; since without the due quantity of pleasurable sensation, flatulency and hypochondriacism affect the intestines, and a languor seizes the arterial pulsations and secretions; as occurs in great and continued anxiety of the mind.

2 . Besides the febrile motions occasioned by irritation, described in Sect. XXXII. and termed irritative fever, it frequently happens that pain is excited by the violence of the fibrous contractions; and other new motions are then superadded, in consequence of sensation, which we shall term febris sensitiva, or sensitive fever. It must be observed, that most irritative fevers begin with a decreased exertion of irritation, owing to defect of stimulus; but that on the contrary the sensitive fevers, or inflammations, generally begin with the increased exertion of sensation, as mentioned in Sect. XXXI. on temperaments: for though the cold fit, which introduces inflammation, commences with decreased irritation, yet the inflammation itself commences in the hot fit during the increase of sensation. Thus a common pustule, or phlegmon, in a part of little sensibility does not excite an inflammatory fever; but if the stomach, intestines, or the tender substance beneath the nails, be injured, great sensation is produced, and the whole system is thrown into that kind of exertion, which constitutes inflammation.

These sensitive fevers, like the irritative ones, resolve themselves into those with arterial strength, and those with arterial debility, that is with excess or defect of sensorial power; these may be termed the febris sensitiva pulsu forti, sensitive fever with strong pulse, which is the synocha, or inflammatory fever; and the febris sensitiva pulsu debili, sensitive fever with weak pulse, which is the typhus gravior, or putrid fever of some writers.

3 . The inflammatory fevers, which are here termed sensitive fevers with strong pulse, are generally attended with some topical inflammation, as pleurisy, peripneumony, or rheumatism, which distinguishes them from irritative fevers with strong pulse. The pulse is strong, quick, and full; for in this fever there is great irritation, as well as great sensation, employed in moving the arterial system. The size, or coagulable lymph, which appears on the blood, is probably an increased secretion from the inflamed internal lining of the whole arterial system, the thinner part being taken away by the increased absorption of the inflamed lymphatics.

The sensitive fevers with weak pulse, which are termed putrid or malignant fevers, are distinguished from irritative fevers with weak pulse, called nervous fevers, described in the last section, as the former consist of inflammation joined with debility, and the latter of debility alone. Hence there is greater heat and more florid colour of the skin in the former, with petechiæ, or purple spots, and aphthæ, or sloughs in the throat, and generally with previous contagion.

When animal matter dies, as a slough in the throat, or the mortified part of a carbuncle, if it be kept moist and warm, as during its abhesion to a living body, it will soon putrify. This, and the origin of contagion from putrid animal substances, seem to have given rise to the septic and antiseptic theory of these fevers.

The matter in pustules and ulcers is thus liable to become putrid, and to produce microscopic animalcula; the urine, if too long retained, may also gain a putrescent smell, as well as the alvine feces; but some writers have gone so far as to believe, that the blood itself in these fevers has smelt putrid, when drawn from the arm of the patient: but this seems not well founded; since a single particle of putrid matter taken into the blood can produce fever, how can we conceive that the whole mass could continue a minute in a putrid state without destroying life? Add to this, that putrid animal substances give up air, as in gangrenes; and that hence if the blood was putrid, air should be given out, which in the blood-vessels is known to occasion immediate death.

In these sensitive fevers with strong pulse (or inflammations) there are two sensorial faculties concerned in producing the disease, viz. irritation and sensation; and hence, as their combined action is more violent, the general quantity of sensorial power becomes further exhausted during the exacerbation, and the system more rapidly weakened than in irritative fever with strong pulse; where the spirit of animation is weakened by but one mode of its exertion: so that this febris sensitiva pulsu forti (or inflammatory fever,) may be considered as the febris irritativa pulsu forti, with the addition of inflammation; and the febris sensitiva pulsu debili (or malignant fever) may be considered as the febris irritativa pulsu debili (or nervous fever), with the addition of inflammation.

4 . In these putrid or malignant fevers a deficiency of irritability accompanies the increase of sensibility; and by this waste of sensorial power by the excess of sensation, which was already too small, arises the delirium and stupor which so perpetually attend these inflammatory fevers with arterial debility. In these cases the voluntary power first ceases to act from deficiency of sensorial spirit; and the stimuli from external bodies have no effect on the exhausted sensorial power, and a delirium like a dream is the consequence. At length the internal stimuli cease to excite sufficient irritation, and the secretions are either not produced at all, or too parsimonious in quantity. Amongst these the secretion of the brain, or production of the sensorial power, becomes deficient, till at last all sensorial power ceases, except what is just necessary to perform the vital motions, and a stupor succeeds; which is thus owing to the same cause as the preceding delirium exerted in a greater degree.

This kind of delirium is owing to a suspension of volition, and to the disobedience of the senses to external stimuli, and is always occasioned by great debility, or paucity of sensorial power; it is therefore a bad sign at the end of inflammatory fevers, which had previous arterial strength, as rheumatism, or pleurisy, as it shews the presence of great exhaustion of sensorial power in a system, which having lately been exposed to great excitement, is not so liable to be stimulated into its healthy action, either by additional stimulus of food and medicines, or by the accumulation of sensorial power during its present torpor. In inflammatory fevers with debility, as those termed putrid fevers, delirium is sometimes, as well as stupor, rather a favourable sign; as less sensorial power is wasted during its continuance (see Class II. 1. 7. 1.), and the constitution not having been previously exposed to excess of stimulation, is more liable to be excited after previous quiescence.

When the sum of general pleasurable sensation becomes too great, another kind of delirium supervenes, and the ideas thus excited are mistaken for the irritations of external objects: such a delirium is produced for a time by intoxicating drugs, as fermented liquors, or opium: a permanent delirium of this kind is sometimes induced by the pleasures of inordinate vanity, or by the enthusiastic hopes of heaven. In these cases the power of volition is incapable of exertion, and in a great degree the external senses become incapable of perceiving their adapted stimuli, because the whole sensorial power is employed or expended on the ideas excited by pleasurable sensation.

This kind of delirium is distinguished from that which attends the fevers above mentioned from its not being accompanied with general debility, but simply with excess of pleasurable sensation; and is therefore in some measure allied to madness or to reverie; it differs from the delirium of dreams, as in this the power of volition is not totally suspended, nor are the senses precluded from external stimulation; there is therefore a degree of consistency, in this kind of delirium, and a degree of attention to external objects, neither of which exist in the delirium of fevers or in dreams.

5 . It would appear, that the vascular system of other animals are less liable to be put into action by their general sum of pleasurable or painful sensation; and that the trains of their ideas, and the muscular motions usually associated with them, are less powerfully connected than in the human system. For other animals neither weep, nor smile, nor laugh; and are hence seldom subject to delirium, as treated of in Sect. XVI. on Instinct. Now as our epidemic and contagious diseases are probably produced by disagreeable sensation, and not simply by irritation; there appears a reason, why brute animals are less liable to epidemic or contagious diseases; and secondly, why none of our contagions, as the small-pox or measles, can be communicated to them, though one of theirs, viz. the hydrophobia, as well as many of their poisons, as those of snakes and of in insects, communicate their deleterious or painful effects to mankind.

Where the quantity of general painful sensation is too great in the system, inordinate voluntary exertions are produced either of our ideas, as in melancholy and madness, or of our muscles, as in convulsion. From these maladies also brute animals are much more exempt than mankind, owing to their greater inaptitude to voluntary exertion, as mentioned in Sect. XVI. on Instinct.

II. 1 . When any moving organ is excited into such violent motions, that a quantity of pleasurable or painful sensation is produced, it frequently happens (but not always) that new motions of the affected organ are generated in consequence of the pain or pleasure, which are termed inflammation.

These new motions are of a peculiar kind, tending to distend the old, and to produce new fibres, and thence to elongate the straight muscles, which serve locomotion, and to form new vessels at the extremities or sides of the vascular muscles.

2 . Thus the pleasurable sensations produce an enlargement of the nipples of nurses, of the papillæ of the tongue, of the penis, and probably produce the growth of the body from its embryon state to its maturity; whilst the new motions in consequence of painful sensation, with the growth of the fibres or vessels, which they occasion, are termed inflammation.

Hence when the straight muscles are inflamed, part of their tendons at each extremity gain new life and sensibility, and thus the muscle is for a time elongated; and inflamed bones become soft, vascular, and sensible. Thus new vessels shoot over the cornea of inflamed eyes, and into scirrhous tumours, when they become inflamed; and hence all inflamed parts grow together by intermixture, and inosculation of the new and old vessels.

The heat is occasioned from the increased secretions either of mucus, or of the fibres, which produce or elongate the vessels. The red colour is owing to the pellucidity of the newly formed vessels, and as the arterial parts of them are probably formed before their correspondent venous parts.

3 . These new motions are excited either from the increased quantity of sensation in consequence of greater fibrous contractions, or from increased sensibility, that is, from the increased quantity of sensorial power in the moving organ. Hence they are induced by great external stimuli, as by wounds, broken bones; and by acrid or infectious materials; or by common stimuli on those organs, which have been some time quiescent; as the usual light of the day inflames the eyes of those, who have been confined in dungeons; and the warmth of a common fire inflames those, who have been previously exposed to much cold.

But these new motions are never generated by that pain, which arises from defect of stimulus, as from hunger, thirst, cold, or inanition, with all those pains, which are termed nervous. Where these pains exist, the motions of the affected part are lessened; and if inflammation succeeds, it is in some distant parts; as coughs are caused by coldness and moisture being long applied to the feet; or it is in consequence of the renewal of the stimulus, as of heat or food, which excites our organs into stronger action after their temporary quiescence; as kibed heels after walking in snow.

4 . But when these new motions of the vascular muscles are exerted with greater violence, and these vessels are either elongated too much or too hastily, a new material is secreted from their extremities, which is of various kinds according to the peculiar animal motions of this new kind of gland, which secretes it; such is the pus laudabile or common matter, the variolous matter, venereal matter, catarrhous matter, and many others.

5 . These matters are the product of an animal process; they are secreted or produced from the blood by certain diseased motions of the extremities of the blood-vessels, and are on that account all of them contagious; for if a portion of any of these matters is transmitted into the circulation, or perhaps only inserted into the skin, or beneath the cuticle of an healthy person, its stimulus in a certain time produces the same kind of morbid motions, by which itself was produced; and hence a similar kind is generated. See Sect. XXXIX. 6. 1.

6 . It is remarkable, that many of these contagious matters are capable of producing a similar disease but once; as the small-pox and measles; and I suppose this is true of all those contagious diseases, which are spontaneously cured by nature in a certain time; for if the body was capable of receiving the disease a second time, the patient must perpetually infect himself by the very matter, which he has himself produced, and is lodged about him; and hence he could never become free from the disease. Something similar to this is seen in the secondary fever of the confluent small-pox; there is a great absorption of variolous matter, a very minute part of which would give the genuine small-pox to another person; but here it only stimulates the system into common fever; like that which common puss, or any other acrid material might occasion.

7 . In the pulmonary consumption, where common matter is daily absorbed, an irritative fever only, without new inflammation, is generally produced; which is terminated like other irritative fevers by sweats, or loose stools. Hence it does not appear, that this absorbed matter always acts as a contagious material producing fresh inflammation or new abscesses. Though there is reason to believe, that the first time any common matter is absorbed, it has this effect, but not the second time, like the variolous matter above mentioned.

This accounts for the opinion, that the pulmonary consumption is sometimes infectious, which opinion was held by the ancients, and continues in Italy at present; and I have myself seen three or four instances, where a husband and wife, who have slept together, and have thus much received each other's breath, who have infected each other, and both died in consequence of the original taint of only one of them. This also accounts for the abscesses in various parts of the body, that are sometimes produced after the inoculated small-pox is terminated; for this second absorption of variolous matter acts like common matter, and produces only irritative fever in those children, whose constitutions have already experienced the absorption of common matter; and inflammation with a tendency to produce new abscesses in those, whose constitutions have not experienced the absorptions of common matter.

It is probable, that more certain proofs might have been found to shew, that common matter is infectious the first time it is absorbed, tending to produce similar abscesses, but not the second time of its absorption, if this subject had been attended to.

8 . These contagious diseases are very numerous, as the plague, small-pox, chicken-pox, measles, scarlet-fever, pemphigus, catarrh, chincough, venereal disease, itch, trichoma, tinea. The infectious material does not seem to be dissolved by the air, but only mixed with it perhaps in fine powder, which soon subsides; since many of these contagions can only be received by actual contact; and others of them only at small distances from the infected person; as is evident from many persons having been near patients of the small-pox without acquiring the disease.

The reason, why many of these diseases are received but once, and others repeatedly, is not well understood; it appears to me, that the constitution becomes so accustomed to the stimuli of these infectious materials, by having once experienced them, that though irritative motions, as hectic fevers, may again be produced by them, yet no sensation, and in consequence no general inflammation succeeds; as disagreeable smells or tastes by habit cease to be perceived; they continue indeed to excite irritative ideas on the organs of sense, but these are not succeeded by sensation.

There are many irritative motions, which were at first succeeded by sensation, but which by frequent repetition cease to excite sensation, as explained in Sect. XX. on Vertigo. And, that this circumstance exists in respect to infectious matter appears from a known fact; that nurses, who have had the small-pox, are liable to experience small ulcers on their arms by the contact of variolous matter in lifting their patients; and that when patients, who have formerly had the small-pox have been inoculated in the arm, a phlegmon, or inflamed sore, has succeeded, but no subsequent fever. Which shews, that the contagious matter of the small-pox has not lost its power of stimulating the part it is applied to, but that the general system is not affected in consequence. See Section XII. 7. 6. XIX. 9.

9 . From the accounts of the plague, virulent catarrh, and putrid dysentery, it seems uncertain, whether these diseases are experienced more than once; but the venereal disease and itch are doubtless repeatedly infectious; and as these diseases are never cured spontaneously, but require medicines, which act without apparent operation, some have suspected, that the contagious material produces similar matter rather by a chemical change of the fluids, than by an animal process; and that the specific medicines destroy their virus by chemically combining with it. This opinion is successfully combated by Mr. Hunter, in his Treatise on Venereal Disease, Part I. c. i.

But this opinion wants the support of analogy, as there is no known process in animal bodies, which is purely chemical, not even digestion; nor can any of these matters be produced by chemical processes. Add to this, that it is probable, that the insects, observed in the pustules of the itch, and in the stools of dysenteric patients, are the consequences, and not the causes of these diseases. And that the specific medicines, which cure the itch and lues venerea, as brimstone and mercury, act only by increasing the absorption of the matter in the ulcuscles of those diseases, and thence disposing them to heal; which would otherwise continue to spread.

Why the venereal disease, and itch, and tenia, or scald head, are repeatedly contagious, while those contagions attended with fever can be received but once, seems to depend on their being rather local diseases than universal ones, and are hence not attended with fever, except the purulent fever in their last stages, when the patient is destroyed by them. On this account the whole of the system does not become habituated to these morbid actions, so as to cease to be affected with sensation by a repetition of the contagion. Thus the contagious matter of the venereal disease, and of the tenia, affects the lymphatic glands, as the inquinal glands, and those about the roots of the hair and neck, where it is arrested, but does not seem to affect the blood-vessels, since no fever ensues.

Hence it would appear, that these kinds of contagion are propagated not by means of the circulation, but by sympathy of distant parts with each other; since if a distant part, as the palate, should be excited by sensitive association into the same kind of motions, as the parts originally affected by the contact of infectious matter; that distant part will produce the same kind of infectious matter; for every secretion from the blood is formed from it by the peculiar motions of the fine extremities of the gland, which secretes it; the various secreted fluids, as the bile, saliva, gastric juice, not previously existing, as such, in the blood-vessels.

And this peculiar sympathy between the genitals and the throat, owing to sensitive association, appears not only in the production of venereal ulcers in the throat, but in variety of other instances, as in the mumps, in the hydrophobia, some coughs, strangulation, the production of the beard, change of voice at puberty. Which are further described in Class IV. 1. 2. 7.

To evince that the production of such large quantities of contagious matter, as are seen in some variolous patients, so as to cover the whole skin almost with pustules, does not arise from any chemical fermentation in the blood, but that it is owing to morbid motions of the fine extremities of the capillaries, or glands, whether these be ruptured or not, appears from the quantity of this matter always corresponding with the quantity of the fever; that is, with the violent exertions of those glands and capillaries, which are the terminations of the arterial system.

The truth of this theory is evinced further by a circumstance observed by Mr. J. Hunter, in his Treatise on Venereal Disease; that in a patient, who was inoculated for the small-pox, and who appeared afterwards to have been previously infested with the measles, the progress of the small-pox was delayed till the measles had run their course, and that then the small-pox went through its usual periods.

Two similar cases fell under my care, which I shall here relate, as it confirms that of Mr. Hunter, and contributes to illustrate this part of the theory of contagious diseases. I have transcribed the particulars from a letter of Mr. Lightwood of Yoxal, the surgeon who daily attended them, and at my request, after I had seen them, kept a kind of journal of their cases.

Miss H. and Miss L. two sisters, the one about four and the other about three years old, were inoculated Feb. 7, 1791. On the 10th there was a redness on both arms discernible by a glass. On the 11th their arms were so much inflamed as to leave no doubt of the infection having taken place. On the 12th less appearance of inflammation on their arms. In the evening Miss L. had an eruption, which resembled the measles. On the 12th the eruption on Miss L. was very full on the face and breast, like the measles, with considerable fever. It was now known, that the measles were in a farm house in the neighbourhood. Miss H.'s arm less inflamed than yesterday. On the 14th Miss L.'s fever great, and the eruption universal. The arm appears to be healed. Miss H.'s arm somewhat redder. They were now put into separate rooms. On the 15th Miss L.'s arms as yesterday. Eruption continues. Miss H.'s arms have varied but little. 16th, the eruptions on Miss L. are dying away, her fever gone. Begins to have a little redness in one arm at the place of inoculation. Miss H.'s arms get redder, but she has no appearance of complaint. 20th, Miss L.'s arms have advanced slowly till this day, and now a few pustules appear. Miss H.'s arm has made little progress from the 16th to this day, and now she has some fever. 21st, Miss L. as yesterday. Miss H. has much inflammation, and an increase of the red circle on one arm to the size of half a crown, and had much fever at night, with fetid breath. 22d, Miss L.'s pustules continue advancing. Miss H.'s inflammation of her arm and red circle increases. A few red spots appear in different parts with some degree of fever this morning, 23d. Miss L. has a larger crop of pustules. Miss H. has small pustules and great inflammation of her arms, with but one pustule likely to suppurate. After this day they gradually got well, and the pustules disappeared.

In one of these cases the measles went through their common course with milder symptoms than usual, and in the other the measly contagion seemed just sufficient to stop the progress of variolous contagion, but without itself throwing the constitution into any disorder. At the same time both the measles and small-pox seem to have been rendered milder. Does not this give an idea, that if they were both inoculated at the same time, that neither of them might affect the patient?

From these cases I contend, that the contagious matter of these diseases does not affect the constitution by a fermentation, or chemical change of the blood, because then they must have proceeded together, and have produced a third something, not exactly similar to either of them: but that they produce new motions of the cutaneous terminations of the blood-vessels, which for a time proceed daily with increasing activity, like some paroxysms of fever, till they at length secrete or form a similar poison by these unnatural actions.

Now as in the measles one kind of unnatural motion takes place, and in the small-pox another kind, it is easy to conceive, that these different kinds of morbid motions cannot exist together; and therefore, that that which has first begun will continue till the system becomes habituated to the stimulus which occasions it, and has ceased to be thrown into action by it; and then the other kind of stimulus will in its turn produce fever, and new kinds of motions peculiar to itself.

10 . On further considering the action of contagious matter, since the former part of this work was sent to the press; where I have asserted, in Sect. XXII. 3. 3. that it is probable, that the variolous matter is diffused through the blood; I prevailed on my friend Mr. Power, surgeon at Bosworth in Leicestershire to try, whether the small-pox could be inoculated by using the blood of a variolous patient instead of the matter from the pustules; as I thought such an experiment might throw some light at least on this interesting subject. The following is an extract from his letter:—

"March 11, 1793. I inoculated two children, who had not had the small-pox, with blood; which was taken from a patient on the second day after the eruption commenced, and before it was completed. And at the same time I inoculated myself with blood from the same person, in order to compare the appearances, which might arise in a person liable to receive the infection, and in one not liable to receive it. On the same day I inoculated four other children liable to receive the infection with blood taken from another person on the fourth day after the commencement of the eruption. The patients from whom the blood was taken had the disease mildly, but had the most pustules of any I could select from twenty inoculated patients; and as much of the blood was insinuated under the cuticle as I could introduce by elevating the skin without drawing blood; and three or four such punctures were made in each of their arms, and the blood was used in its fluid state.

"As the appearances in all these patients, as well as in myself, were similar, I shall only mention them in general terms. March 13. A slight subcuticular discoloration, with rather a livid appearance, without soreness or pain, was visible in them all, as well as in my own hand. 15. The discoloration somewhat less, without pain or soreness. Some patients inoculated on the same day with variolous matter have considerable inflammation. 17. The discoloration is quite gone in them all, and from my own hand, a dry mark only remaining. And they were all inoculated on the 18th, with variolous matter, which produced the disease in them all."

Mr. Power afterwards observes, that, as the patients from whom the blood was taken had the disease mildly, it may be supposed, that though the contagious matter might be mixed with the blood, it might still be in too dilute a state to convey the infection; but adds at the same time, that he has diluted recent matter with at least five times its quantity of water, and which has still given the infection; though he has sometimes diluted it so far as to fail.

The following experiments were instituted at my request by my friend Mr. Hadley, surgeon in Derby, to ascertain whether the blood of a person in the small-pox be capable of communicating the disease. "Experiment 1st. October 18th, 1793. I took some blood from a vein in the arm of a person who had the small-pox, on the second day of the eruption, and introduced a small quantity of it immediately with the point of a lancet between the scars and true skin of the right arm of a boy nine years old in two or three different places; the other arm was inoculated with variolous matter at the same time.

"19th. The punctured parts of the right arm were surrounded with some degree of subcuticular inflammation. 20th. The inflammation more considerable, with a slight degree of itching, but no pain upon pressure. 21st. Upon examining the arm this day with a lens I found the inflammation less extensive, and the redness changing to a deep yellow or orange-colour, 22d. Inflammation nearly gone. 23d. Nothing remained, except a slight discoloration and a little scurfy appearance on the punctures. At the same time the inflammation of the arm inoculated with variolous matter was increasing fast, and he had the disease mildly at the usual time.

"Experiment 2d. I inoculated another child at the same time and in the same manner, with blood taken on the first day of the eruption; but as the appearance and effects were similar to those in the preceding experiment, I shall not relate them minutely.

"Experiment 3d. October 20th. Blood was taken from a person who had the small-pox, on the third day of the eruption, and on the sixth from the commencement of the eruptive fever. I introduced some of it in its fluid state into both arms of a boy seven years old.

21st. There appeared to be some inflammation under the cuticle, where the punctures were made. 22d. Inflammation more considerable. 23d. On this day the inflammation was somewhat greater, and the cuticle rather elevated.

"24th. Inflammation much less, and only a brown or orange-colour remained. 25th. Scarcely any discoloration left. On this day he was inoculated with variolous matter, the progress of the infection went on in the usual way, and he had the small-pox very favourably.

"At this time I was requested to inoculate a young person, who was thought to have had the small-pox, but his parents were not quite certain; in one arm I introduced variolous matter, and in the other blood, taken as in experiment 3d. On the second day after the operation, the punctured parts were inflamed, though I think the arm in which I had inserted variolous matter was rather more so than the other. On the third the inflammation was increased, and looked much the same as in the preceding experiment. 4th. The inflammation was much diminished, and on the 5th almost gone. He was exposed at the same time to the natural infection, but has continued perfectly well.

"I have frequently observed (and believe most practitioners have done the same), that if variolous matter be inserted in the arm of a person who has previously had the small-pox, that the inflammation on the second or third days is much greater, than if they had not had the disease, but on the fourth or fifth it disappears.

"On the 23d I introduced blood into the arms of three more children, taken on the third and fourth days of the eruption. The appearances were much the same as mentioned in experiments first and third. They were afterwards inoculated with variolous matter, and had the disease in the regular way.

"The above experiments were made with blood taken from a small vein in the hand or foot of three or four different patients, whom I had at that time under inoculation. They were selected from 160, as having the greatest number of pustules. The part was washed with warm water before the blood was taken, to prevent the possibility of any matter being mixed with it from the surface."

Shall we conclude from hence, that the variolous matter never enters the blood-vessels? but that the morbid motions of the vessels of the skin around the insertion of it continue to increase in a larger and larger circle for six or seven days; that then their quantity of morbid action becomes great enough to produce a fever-fit, and to affect the stomach by association of motions? and finally, that a second association of motions is produced between the stomach and the other parts of the skin, inducing them into morbid actions similar to those of the circle round the insertion of the variolous matter? Many more experiments and observations are required before this important question can be satisfactorily answered.

It may be adduced, that as the matter inserted into the skin of the arm frequently swells the lymphatic in the axilla, that in that circumstance it seems to be there arrested in its progress, and cannot be imagined to enter the blood by that lymphatic gland till the swelling of it subsides. Some other phænomena of the disease are more easily reconcileable to this theory of sympathetic motions than to that of absorption; as the time taken up between the insertion of the matter, and the operation of it on the system, as mentioned above. For the circle around the insertion is seen to increase, and to inflame; and I believe, undergoes a kind of diurnal paroxysm of torpor and paleness with a succeeding increase of action and colour, like a topical fever-fit. Whereas if the matter is conceived to circulate for six or seven days with the blood, without producing disorder, it ought to be rendered milder, or the blood-vessels more familiarized to its acrimony.

It is much easier to conceive from this doctrine of associated or sympathetic motions of distant parts of the system, how it happens, that the variolous infection can be received but once, as before explained; than by supposing, that a change is effected in the mass of blood by any kind of fermentative process.

The curious circumstance of the two contagions of small-pox and measles not acting at the same time, but one of them resting or suspending its action till that of the other ceases, may be much easier explained from sympathetic or associated actions of the infected part with other parts of the system, than it can from supposing the two contagions to enter the circulation.

The skin of the face is subject to more frequent vicissitudes of heat and cold, from its exposure to the open air, and is in consequence more liable to sensitive association with the stomach than any other part of the surface of the body, because their actions have been more frequently thus associated. Thus in a surfeit from drinking cold water, when a person is very hot and fatigued, an eruption is liable to appear on the face in consequence of this sympathy. In the same manner the rosy eruption on the faces of drunkards more probably arises from the sympathy of the face with the stomach, rather than between the face and the liver, as is generally supposed.

This sympathy between the stomach and the skin of the face is apparent in the eruption of the small-pox; since, where the disease is in considerable quantity, the eruption on the face first succeeds the sickness of the stomach. In the natural disease the stomach seems to be frequently primarily affected, either alone or along with the tonsils, as the matter seems to be only diffused in the air, and by being mixed with the saliva, or mucus of the tonsils, to be swallowed into the stomach.

After some days the irritative circles of motions become disordered by this new stimulus, which acts upon the mucus lining of the stomach; and sickness, vertigo, and a diurnal fever succeed. These disordered irritative motions become daily increased for two or three days, and then by their increased action certain sensitive motions, or inflammation, is produced, and at the next cold fit of fever, when the stomach recovers from its torpor, an inflammation of the external skin is formed in points (which afterwards suppurate), by sensitive association, in the same manner as a cough is produced in consequence of exposing the feet to cold, as described in Sect. XXV. 17. and Class IV. 2. 1. 7. If the inoculated skin of the arm, as far as it appears inflamed, was to be cut out, or destroyed by caustic, before the fever commenced, as suppose on the fourth day after inoculation, would this prevent the disease? as it is supposed to prevent the hydrophobia.

III. 1 . Where the new vessels, and enlarged old ones, which constitute inflammation, are not so hastily distended as to burst, and form a new kind of gland for the secretion of matter, as above mentioned; if such circumstances happen as diminish the painful sensation, the tendency to growth ceases, and by and by an absorption commences, not only of the superabundant quantity of fluids deposited in the inflamed part, but of the solids likewise, and this even of the hardest kind.

Thus during the growth of the second set of teeth in children, the roots of the first set are totally absorbed, till at length nothing of them remains but the crown; though a few weeks before, if they are drawn immaturely, their roots are found complete. Similar to this Mr. Hunter has observed, that where a dead piece of bone is to exfoliate, or to separate from a living one, that the dead part does not putrify, but remains perfectly sound, while the surface of the living part of the bone, which is in contact with the dead part, becomes absorbed, and thus effects its separation. Med. Comment. Edinb. V. 1. 425. In the same manner the calcareous matter of gouty concretions, the coagulable lymph deposited on inflamed membranes in rheumatism and extravasated blood become absorbed; which are all as solid and as indissoluble materials as the new vessels produced in inflammation.

This absorption of the new vessels and deposited fluids of inflamed parts is called resolution: it is produced by first using such internal means as decrease the pain of the part, and in consequence its new motions, as repeated bleeding, cathartics, diluent potations, and warm bath.

After the vessels are thus emptied, and the absorption of the new vessels and deposited fluids is evidently begun, it is much promoted by stimulating the part externally by solutions of lead, or other metals, and internally by the bark, and small doses of opium. Hence when an ophthalmy begins to become paler, any acrid eye-water, as a solution of six grains of white vitriol in an ounce of water, hastens the absorption, and clears the eye in a very short time. But the same application used a few days sooner would have increased the inflammation. Hence after evacuation opium in small doses may contribute to promote the absorption of fluids deposited on the brain, as observed by Mr. Bromfield in his treatise of surgery.

2 . Where an abscess is formed by the rupture of these new vessels, the violence of inflammation ceases, and a new gland separates a material called pus: at the same time a less degree of inflammation produces new vessels called vulgarly proud flesh; which, if no bandage confines its growth, nor any other circumstance promotes absorption in the wound, would rise to a great height above the usual size of the part.

Hence the art of healing ulcers consists in producing a tendency to absorption in the wound greater than the deposition. Thus when an ill-conditioned ulcer separates a copious and thin discharge, by the use of any stimulus, as of salts of lead, or mercury, or copper externally applied, the discharge becomes diminished in quantity, and becomes thicker, as the thinner parts are first absorbed.

But nothing so much contributes to increase the absorption in a wound as covering the whole limb above the sore with a bandage, which should be spread with some plaster, as with emplastrum de minio, to prevent it from slipping. By this artificial tightness of the skin, the arterial pulsations act with double their usual power in promoting the ascending current of the fluid in the valvular lymphatics.

Internally the absorption from ulcers should be promoted first by evacuation, then by opium, bark, mercury, steel.

3 . Where the inflammation proceeds with greater violence or rapidity, that is, when by the painful sensation a more inordinate activity of the organ is produced, and by this great activity an additional quantity of painful sensation follows in an increasing ratio, till the whole of the sensorial power, or spirit of animation, in the part becomes exhausted, a mortification ensues, as in a carbuncle, in inflammations of the bowels, in the extremities of old people, or in the limbs of those who are brought near a fire after having been much benumbed with cold. And from hence it appears, why weak people are more subject to mortification than strong ones, and why in weak persons less pain will produce mortification, namely, because the sensorial power is sooner exhausted by any excess of activity. I remember seeing a gentleman who had the preceding day travelled two stages in a chaise with what he termed a bearable pain in his bowels; which when I saw him had ceased rather suddenly, and without a passage through him; his pulse was then weak, though not very quick; but as nothing which he swallowed would continue in his stomach many minutes, I concluded that the bowel was mortified; he died on the next day. It is usual for patients sinking under the small-pox with mortified pustules, and with purple spots intermixed, to complain of no pain, but to say they are pretty well to the last moment.

Recapitulation.

IV. When the motions of any part of the system, in consequence of previous torpor, are performed with more energy than in the irritative fevers, a disagreeable sensation is produced, and new actions of some part of the system commence in consequence of this sensation conjointly with the irritation: which motions constitute inflammation. If the fever be attended with a strong pulse, as in pleurisy, or rheumatism, it is termed synocha sensitiva, or sensitive fever with strong pulse; which is usually termed inflammatory fever. If it be attended with weak pulse, it is termed typhus sensitivus, or sensitive fever with weak pulse, or typhus gravior, or putrid malignant fever.

The synocha sensitiva, or sensitive fever with strong pulse, is generally attended with some topical inflammation, as in peripneumony, hepatitis, and is accompanied with much coagulable lymph, or size; which rises to the surface of the blood, when taken into a bason, as it cools; and which is believed to be the increased mucous secretion from the coats of the arteries, inspissated by a greater absorption of its aqueous and saline part, and perhaps changed by its delay in the circulation.

The typhus sensitivus, or sensitive fever with weak pulse, is frequently attended with delirium, which is caused by the deficiency of the quantity of sensorial power, and with variety of cutaneous eruptions.

Inflammation is caused by the pains occasioned by excess of action, and not by those pains which are occasioned by defect of action. These morbid actions, which are thus produced by two sensorial powers, viz. by irritation and sensation, secrete new living fibres, which elongate the old vessels, or form new ones, and at the same time much heat is evolved from these combinations. By the rupture of these vessels, or by a new construction of their apertures, purulent matters are secreted of various kinds; which are infectious the first time they are applied to the skin beneath the cuticle, or swallowed with the saliva into the stomach. This contagion acts not by its being absorbed into the circulation, but by the sympathies, or associated actions, between the part first stimulated by the contagious matter and the other parts of the system. Thus in the natural small-pox the contagion is swallowed with the saliva, and by its stimulus inflames the stomach; this variolous inflammation of the stomach increases every day, like the circle round the puncture of an inoculated arm, till it becomes great enough to disorder the circles of irritative and sensitive motions, and thus produces fever-fits, with sickness and vomiting. Lastly, after the cold paroxysm, or fit of torpor, of the stomach has increased for two or three successive days, an inflammation of the skin commences in points; which generally first appear upon the face, as the associated actions between the skin of the face and that of the stomach have been more frequently exerted together than those of any other parts of the external surface.

Contagious matters, as those of the measles and small-pox, do not act upon the system at the same time; but the progress of that which was last received is delayed, till the action of the former infection ceases. All kinds of matter, even that from common ulcers, are probably contagious the first time they are inserted beneath the cuticle or swallowed into the stomach; that is, as they were formed by certain morbid actions of the extremities of the vessels, they have the power to excite similar morbid actions in the extremities of other vessels, to which they are applied; and these by sympathy, or associations of motion, excite similar morbid actions in distant parts of the system, without entering the circulation; and hence the blood of a patient in the small-pox will not give that disease by inoculation to others.

When the new fibres or vessels become again absorbed into the circulation, the inflammation ceases; which is promoted, after sufficient evacuations, by external stimulants and bandages: but where the action of the vessels is very great, a mortification of the part is liable to ensue, owing to the exhaustion of sensorial power; which however occurs in weak people without much pain, and without very violent previous inflammation; and, like partial paralysis, may be esteemed one mode of natural death of old people, a part dying before the whole.

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title: Zoonomia/I.XXXIII


text:
Zoonomia/I.XXXIV

SECT. XXXIV.

DISEASES OF VOLITION.

 * I. 1. Volition defined. Motions termed involuntary are caused by volition. Desires opposed to each other. Deliberation. Ass between two hay-cocks. Saliva swallowed against one's desire. Voluntary motions distinguished from those associated with sensitive motions. 2. Pains from excess, and from defect of motion. No pain is felt during vehement voluntary exertion; as in cold fits of ague, labour-pains, strangury, tenesmus, vomiting, restlessness in fevers, convulsion of a wounded muscle. 3. Of holding the breath and screaming in pain; why swine and dogs cry out in pain, and not sheep and horses. Of grinning and biting in pain; why mad animals bite others. 4. Epileptic convulsions explained, why the fits begin with quivering of the under jaw, biting the tongue, and setting the teeth; why the convulsive motions are alternately relaxed. The phenomenon of laughter explained. Why children cannot tickle themselves. How some have died from immoderate laughter. 5. Of cataleptic spasms, of the locked jaw, of painful cramps. 6. Syncope explained. Why no external objects are perceived in syncope. 7. Of palsy and apoplexy from violent exertions. Case of Mrs. Scot. From dancing, scating, swimming. Case of Mr. Nairn. Why palsies are not always immediately preceded by violent exertions. Palsy and epilepsy from diseased livers. Why the right arm more frequently paralytic than the left. How paralytic limbs regain their motions. II. Diseases of the sensual motions from excess or defect of voluntary exertion. 1. Madness. 2. Distinguished from delirium. 3. Why mankind more liable to insanity than brutes. 4. Suspicion. Want of shame, and of cleanliness. 5. They bear cold, hunger, and fatigue. Charles XII. of Sweden. 6. Pleasureable delirium, and insanity. Child riding on a stick. Pains of martyrdom not felt. 7. Dropsy. 8. Inflammation cured by insanity. III. 1. Pain relieved by reverie. Reverie is an exertion of voluntary and sensitive motions. 2. Case of reverie. 3. Lady supposed to have two souls. 4. Methods of relieving pain.

I. 1 . Before we commence this Section on Diseased Voluntary Motions, it may be necessary to premise, that the word volition is not used in this work exactly in its common acceptation. Volition is said in Section V. to bear the same analogy to desire and aversion, which sensation does to pleasure and pain. And hence that, when desire or aversion produces any action of the muscular fibres, or of the organs of sense, they are termed volition; and the actions produced in consequence are termed voluntary actions. Whence it appears, that motions of our muscles or ideas may be produced in consequence of desire or aversion without our having the power to prevent them, and yet these motions may be termed voluntary, according to our definition of the word; though in common language they would be called involuntary.

The objects of desire and aversion are generally at a distance, whereas those of pleasure and pain are immediately acting upon our organs. Hence, before desire or aversion are exerted, so as to cause any actions, there is generally time for deliberation; which consists in discovering the means to obtain the object of desire, or to avoid the object of aversion; or in examining the good or bad consequences, which may result from them. In this case it is evident, that we have a power to delay the proposed action, or to perform it; and this power of choosing, whether we shall act or not, is in common language expressed by the word volition, or will. Whereas in this work the word volition means simply the active state of the sensorial faculty in producing motion in consequence of desire or aversion: whether we have the power of restraining that action, or not; that is, whether we exert any actions in consequence of opposite desires or aversions, or not.

For if the objects of desire or aversion are present, there is no necessity to investigate or compare the means of obtaining them, nor do we always deliberate about their consequences; that is, no deliberation necessarily intervenes, and in consequence the power of choosing to act or not is not exerted. It is probable, that this twofold use of the word volition in all languages has confounded the metaphysicians, who have disputed about free will and necessity. Whereas from the above analysis it would appear, that during our sleep, we use no voluntary exertions at all; and in our waking hours, that they are the consequence of desire or aversion.

To will is to act in consequence of desire; but to desire means to desire something, even if that something be only to become free from the pain, which causes the desire; for to desire nothing is not to desire; the word desire, therefore, includes both the action and the object or motive; for the object and motive of desire are the same thing. Hence to desire without an object, that is, without a motive, is a solecism in language. As if one should ask, if you could eat without food, or breathe without air.

From this account of volition it appears, that convulsions of the muscles, as in epileptic fits, may in the common sense of that word be termed involuntary; because no deliberation is interposed between the desire or aversion and the consequent action; but in the sense of the word, as above defined, they belong to the class of voluntary motions, as delivered in Vol. II. Class III. If this use of the word be discordant to the ear of the reader, the term morbid voluntary motions, or motions in consequence of aversion, may be substituted in its stead.

If a person has a desire to be cured of the ague, and has at the same time an aversion (or contrary desire) to swallowing an ounce of Peruvian bark; he balances desire against desire, or aversion against aversion; and thus he acquires the power of choosing, which is the common acceptation of the word willing. But in the cold fit of ague, after having discovered that the act of shuddering, or exerting the subcutaneous muscles, relieves the pain of cold; he immediately exerts this act of volition, and shudders, as soon as the pain and consequent aversion return, without any deliberation intervening; yet is this act, as well as that of swallowing an ounce of the bark, caused by volition; and that even though he endeavours in vain to prevent it by a weaker contrary volition. This recalls to our minds the story of the hungry ass between two hay-stacks, where the two desires are supposed so exactly to counteract each other, that he goes to neither of the stacks, but perishes by want. Now as two equal and opposite desires are thus supposed to balance each other, and prevent all action, it follows, that if one of these hay-stacks was suddenly removed, that the ass would irresistibly be hurried to the other, which in the common use of the word might be called an involuntary act; but which, in our acceptation of it, would be classed amongst voluntary actions, as above explained.

Hence to deliberate is to compare opposing desires or aversions, and that which is the most interesting at length prevails, and produces action. Similar to this, where two pains oppose each other, the stronger or more interesting one produces action; as in pleurisy the pain from suffocation would produce expansion of the lungs, but the pain occasioned by extending the inflamed membrane, which lines the chest, opposes this expansion, and one or the other alternately prevails.

When any one moves his hand quickly near another person's eyes, the eye-lids instantly close; this act in common language is termed involuntary, as we have not time to deliberate or to exert any contrary desire or aversion, but in this work it would be termed a voluntary act, because it is caused by the faculty of volition, and after a few trials the nictitation can be prevented by a contrary or opposing volition.

The power of opposing volitions is best exemplified in the story of Mutius Scævola, who is said to have thrust his hand into the fire before Porcenna, and to have suffered it to be consumed for having failed him in his attempt on the life of that general. Here the aversion for the loss of same, or the unsatisfied desire to serve his country, the two prevalent enthusiasms at that time, were more powerful than the desire of withdrawing his hand, which must be occasioned by the pain of combustion; of these opposing volitions

Vincit amor patriæ, laudumque immensa cupido.

If any one is told not to swallow his saliva for a minute, he soon swallows it contrary to his will, in the common sense of that word; but this also is a voluntary action, as it is performed by the faculty of volition, and is thus to be understood. When the power of volition is exerted on any of our senses, they become more acute, as in our attempts to hear small noises in the night. As explained in Section XIX. 6. Hence by our attention to the fauces from our desire not to swallow our saliva; the fauces become more sensible; and the stimulus of the saliva is followed by greater sensation, and consequent desire of swallowing it. So that the desire or volition in consequence of the increased sensation of the saliva is more powerful, than the previous desire not to swallow it. See Vol. II. Deglutitio invita. In the same manner if a modest man wishes not to want to make water, when he is confined with ladies in a coach or an assembly-room; that very act of volition induces the circumstance, which he wishes to avoid, as above explained; insomuch that I once saw a partial insanity, which might be called a voluntary diabetes, which was occasioned by the fear (and consequent aversion) of not being able to make water at all.

It is further necessary to observe here, to prevent any confusion of voluntary, with sensitive, or associate motions, that in all the instances of violent efforts to relieve pain, those efforts are at first voluntary exertions; but after they have been frequently repeated for the purpose of relieving certain pains, they become associated with those pains, and cease at those times to be subservient to the will; as in coughing, sneezing, and strangury. Of these motions those which contribute to remove or dislodge the offending cause, as the actions of the abdominal muscles in parturition or in vomiting, though they were originally excited by volition, are in this work termed sensitive motions; but those actions of the muscles or organs of sense, which do not contribute to remove the offending cause, as in general convulsions or in madness, are in this work termed voluntary motions, or motions in consequence of aversion, though in common language they are called involuntary ones. Those sensitive unrestrainable actions, which contribute to remove the cause of pain are uniformly and invariably exerted, as in coughing or sneezing; but those motions which are exerted in consequence of aversion without contributing to remove the painful cause, but only to prevent the sensation of it, as in epileptic, or cataleptic fits, are not uniformly and invariably exerted, but change from one set of muscles to another, as will be further explained; and may by this criterion also be distinguished from the former.

At the same time those motions, which are excited by perpetual stimulus, or by association with each other, or immediately by pleasureable or painful sensation, may properly be termed involuntary motions, as those of the heart and arteries; as the faculty of volition seldom affects those, except when it exists in unnatural quantity, as in maniacal people.

2 . It was observed in Section XIV. on the Production of Ideas, that those parts of the system, which are usually termed the organs of sense, are liable to be excited into pain by the excess of the stimulus of those objects, which are by nature adapted to affect them; as of too great light, sound, or pressure. But that these organs receive no pain from the defect or absence of these stimuli, as in darkness or silence. But that our other organs of perception, which have generally been called appetites, as of hunger, thirst, want of heat, want of fresh air, are liable to be affected with pain by the defect, as well as by the excess of their appropriated stimuli.

This excess or defect of stimulus is however to be considered only as the remote cause of the pain, the immediate cause being the excess or defect of the natural action of the affected part, according to Sect. IV. 5. Hence all the pains of the body may be divided into those from excess of motion, and those from defect of motion; which distinction is of great importance in the knowledge and the cure of many diseases. For as the pains from excess of motion either gradually subside, or are in general succeeded by inflammation; so those from defect of motion either gradually subside, or are in general succeeded by convulsion, or madness. These pains are easily distinguishable from each other by this circumstance, that the former are attended with heat of the pained part, or of the whole body; whereas the latter exists without increase of heat in the pained part, and is generally attended with coldness of the extremities of the body; which is the true criterion of what have been called nervous pains.

Thus when any acrid material, as snuff or lime, falls into the eye, pain and inflammation and heat are produced from the excess of stimulus; but violent hunger, hemicrania, or the clavus hystericus, are attended with coldness of the extremities, and defect of circulation. When we are exposed to great cold, the pain we experience from the deficiency of heat is attended with a quiescence of the motions of the vascular system; so that no inflammation is produced, but a great desire of heat, and a tremulous motion of the subcutaneous muscles, which is properly a convulsion in consequence of this pain from defect of the stimulus of heat.

It was before mentioned, that as sensation consists in certain movements of the sensorium, beginning at some of the extremities of it, and propagated to the central parts of it; so volition consists of certain other movements of the sensorium, commencing in the central parts of it, and propagated to some of its extremities. This idea of these two great powers of motion in the animal machine is confirmed from observing, that they never exist in a great degree or universally at the same time; for while we strongly exert our voluntary motions, we cease to feel the pains or uneasinesses, which occasioned us to exert them.

Hence during the time of fighting with fists or swords no pain is felt by the combatants, till they cease to exert themselves. Thus in the beginning of ague-fits the painful sensation of cold is diminished, while the patient exerts himself in the shivering and gnashing of his teeth. He then ceases to exert himself, and the pain of cold returns; and he is thus perpetually induced to reiterate these exertions, from which he experiences a temporary relief. The same occurs in labour-pains, the exertion of the parturient woman relieves the violence of the pains for a time, which recur again soon after she has ceased to use those exertions. The same is true in many other painful diseases, as in the strangury, tenesmus, and the efforts of vomiting; all these disagreeable sensations are diminished or removed for a time by the various exertions they occasion, and recur alternately with those exertions.

The restlessness in some fevers is an almost perpetual exertion of this kind, excited to relieve some disagreeable sensations; the reciprocal opposite exertions of a wounded worm, the alternate emprosthotonos and opisthotonos of some spasmodic diseases, and the intervals of all convulsions, from whatever cause, seem to be owing to this circumstance of the laws of animation; that great or universal exertion cannot exist at the same time with great or universal sensation, though they can exist reciprocally; which is probably resolvable into the more general law, that the whole sensorial power being expended in one mode of exertion, there is none to spare for any other. Whence syncope, or temporary apoplexy, succeeds to epileptic convulsions.

3 . Hence when any violent pain afflicts us, of which we can neither avoid nor remove the cause, we soon learn to endeavour to alleviate it, by exerting some violent voluntary effort, as mentioned above; and are naturally induced to use those muscles for this purpose, which have been in the early periods of our lives most frequently or most powerfully exerted.

Now the first muscles, which infants use most frequently, are those of respiration; and on this account we gain a habit of holding our breath, at the same time that we use great efforts to exclude it, for this purpose of alleviating unavoidable pain; or we press out our breath through a small aperture of the larynx, and scream violently, when the pain is greater than is relievable by the former mode of exertion. Thus children scream to relieve any pain either of body or mind, as from anger, or fear of being beaten.

Hence it is curious to observe, that those animals, who have more frequently exerted their muscles of respiration violently, as in talking, barking, or grunting, as children, dogs, hogs, scream much more, when they are in pain, than those other animals, who use little or no language in their common modes of life; as horses, sheep, and cows.

The next most frequent or most powerful efforts, which infants are first tempted to produce, are those with the muscles in biting hard substances; indeed the exertion of these muscles is very powerful in common mastication, as appears from the pain we receive, if a bit of bone is unexpectedly found amongst our softer food; and further appears from their acting to so great mechanical disadvantage, particularly when we bite with the incisores, or canine teeth; which are first formed, and thence are first used to violent exertion.

Hence when a person is in great pain, the cause of which he cannot remove, he sets his teeth firmly together, or bites some substance between them with great vehemence, as another mode of violent exertion to produce a temporary relief. Thus we have a proverb where no help can be had in pain, "to grin and abide;" and the tortures of hell are said to be attended with "gnashing of teeth."

Hence in violent spasmodic pains I have seen people bite not only their tongues, but their arms or fingers, or those of the attendants, or any object which was near them; and also strike, pinch, or tear, others or themselves, particularly the part of their own body, which is painful at the time. Soldiers, who die of painful wounds in battle, are said in Homer to bite the ground. Thus also in the bellon, or colica saturnina, the patients are said to bite their own flesh, and dogs in this disease to bite up the ground they lie upon. It is probable that the great endeavours to bite in mad dogs, and the violence of other mad animals, is owing to the same cause.

4 . If the efforts of our voluntary motions are exerted with still greater energy for the relief of some disagreeable sensation, convulsions are produced; as the various kinds of epilepsy, and in some hysteric paroxysms. In all these diseases a pain, or disagreeable sensation is produced, frequently by worms, or acidity in the bowels, or by a diseased nerve in the side, or head, or by the pain of a diseased liver.

In some constitutions a more intolerable degree of pain is produced in some part at a distance from the cause by sensitive association, as before explained; these pains in such constitutions arise to so great a degree, that I verily believe no artificial tortures could equal some, which I have witnessed; and am confident life would not have long been preserved, unless they had been soon diminished or removed by the universal convulsion of the voluntary motions, or by temporary madness.

In some of the unfortunate patients I have observed, the pain has risen to an inexpressible degree, as above described, before the convulsions have supervened; and which were preceded by screaming, and grinning; in others, as in the common epilepsy, the convulsion has immediately succeeded the commencement of the disagreeable sensations; and as a stupor frequently succeeds the convulsions, they only seemed to remember that a pain at the stomach preceded the fit, or some other uneasy feel; or more frequently retained no memory at all of the immediate cause of the paroxysm. But even in this kind of epilepsy, where the patient does not recollect any preceding pain, the paroxysms generally are preceded by a quivering motion of the under jaw, with a biting of the tongue; the teeth afterwards become pressed together with vehemence, and the eyes are then convulsed, before the commencement of the universal convulsion; which are all efforts to relieve pain.

The reason why these convulsive motions are alternately exerted and remitted was mentioned above, and in Sect. XII. 1. 3. when the exertions are such as give a temporary relief to the pain, which excites them, they cease for a time, till the pain is again perceived; and then new exertions are produced for its relief. We see daily examples of this in the loud reiterated laughter of some people; the pleasureable sensation, which excites this laughter, arises for a time so high as to change its name and become painful: the convulsive motions of the respiratory muscles relieve the pain for a time; we are, however, unwilling to lose the pleasure, and presently put a stop to this exertion, and immediately the pleasure recurs, and again as instantly rises into pain. All of us have felt the pain of immoderate laughter; children have been tickled into convulsions of the whole body; and others have died in the act of laughing; probably from a paralysis succeeding the long continued actions of the muscles of respiration.

Hence we learn the reason, why children, who are so easily excited to laugh by the tickling of other people's fingers, cannot tickle themselves into laughter. The exertion of their hands in the endeavour to tickle themselves prevents the necessity of any exertion of the respiratory muscles to relieve the excess of pleasurable affection. See Sect. XVII. 3. 5.

Chrysippus is recorded to have died laughing, when an ass was invited to sup with him. The same is related of one of the popes, who, when he was ill, saw a tame monkey at his bedside put on the holy thiara. Hall. Phys. T. III. p. 306.

There are instances of epilepsy being produced by laughing recorded by Van Swieten, T. III. 402 and 308. And it is well known, that many people have died instantaneously from the painful excess of joy, which probably might have been prevented by the exertions of laughter.

Every combination of ideas, which we attend to, occasions pain or pleasure; those which occasion pleasure, furnish either social or selfish pleasure, either malicious or friendly, or lascivious, or sublime pleasure; that is, they give us pleasure mixed with other emotions, or they give us unmixed pleasure, without occasioning any other emotions or exertions at the same time. This unmixed pleasure, if it be great, becomes painful, like all other animal motions from stimuli of every kind; and if no other exertions are occasioned at the same time, we use the exertion of laughter to relieve this pain. Hence laughter is occasioned by such wit as excites simple pleasure without any other emotion, such as pity, love, reverence. For sublime ideas are mixed with admiration, beautiful ones with love, new ones with surprise; and these exertions of our ideas prevent the action of laughter from being necessary to relieve the painful pleasure above described. Whence laughable wit consists of frivolous ideas, without connections of any consequence, such as puns on words, or on phrases, incongruous junctions of ideas; on which account laughter is so frequent in children.

Unmixed pleasure less than that, which causes laughter, causes sleep, as in singing children to sleep, or in slight intoxication from wine or food. See Sect. XVIII. 12.

5 . If the pains, or disagreeable sensations, above described do not obtain a temporary relief from these convulsive exertions of the muscles, those convulsive exertions continue without remission, and one kind of catalepsy is produced. Thus when a nerve or tendon produces great pain by its being inflamed or wounded, the patient sets his teeth firmly together, and grins violently, to diminish the pain; and if the pain is not relieved by this exertion, no relaxation of the maxillary muscles takes place, as in the convulsions above described, but the jaws remain firmly fixed together. This locked jaw is the most frequent instance of cataleptic spasm, because we are more inclined to exert the muscles subservient to mastication from their early obedience to violent efforts of volition.

But in the case related in Sect. XIX. on Reverie, the cataleptic lady had pain in her upper teeth; and pressing one of her hands vehemently against her cheek-bone to diminish this pain, it remained in that attitude for about half an hour twice a day, till the painful paroxysm was over.

I have this very day seen a young lady in this disease, (with which she has frequently been afflicted,) she began to-day with violent pain shooting from one side of the forehead to the occiput, and after various struggles lay on the bed with her fingers and wrists bent and stiff for about two hours; in other respects she seemed in a syncope with a natural pulse. She then had intervals of pain and of spasm, and took three grains of opium every hour till she had taken nine grains, before the pains and spasm ceased.

There is, however, another species of fixed spasm, which differs from the former, as the pain exists in the contracted muscle, and would seem rather to be the consequence than the cause of the contraction, as in the cramp in the calf of the leg, and in many other parts of the body.

In these spasms it should seem, that the muscle itself is first thrown into contraction by some disagreeable sensation, as of cold; and that then the violent pain is produced by the great contraction of the muscular fibres extending its own tendons, which are said to be sensible to extension only; and is further explained in Sect. XVIII. 15.

6 . Many instances have been given in this work, where after violent motions excited by irritation, the organ has become quiescent to less, and even to the great irritation, which induced it into violent motion; as after looking long at the sun or any bright colour, they cease to be seen; and after removing from bright day-light into a gloomy room, the eye cannot at first perceive the objects, which stimulate it less. Similar to this is the syncope, which succeeds after the violent exertions of our voluntary motions, as after epileptic fits, for the power of volition acts in this case as the stimulus in the other. This syncope is a temporary palsy, or apoplexy, which ceases after a time, the muscles recovering their power of being excited into action by the efforts of volition; as the eye in the circumstance above mentioned recovers in a little time its power of seeing objects in a gloomy room; which were invisible immediately after coming out of a stronger light. This is owing to an accumulation of sensorial power during the inaction of those fibres, which were before accustomed to perpetual exertions, as explained in Sect. XII. 7. 1. A slighter degree of this disease is experienced by every one after great fatigue, when the muscles gain such inability to further action, that we are obliged to rest them for a while, or to summon a greater power of volition to continue their motions.

In all the syncopes, which I have seen induced after convulsive fits, the pulse has continued natural, though the organs of sense, as well as the locomotive muscles, have ceased to perform their functions; for it is necessary for the perception of objects, that the external organs of sense should be properly excited by the voluntary power, as the eye-lids must be open, and perhaps the muscles of the eye put into action to distend, and thence give greater pellucidity to the cornea, which in syncope, as in death, appears flat and less transparent.

The tympanum of the ear also seems to require a voluntary exertion of its muscles, to gain its due tension, and it is probable the other external organs of sense require a similar voluntary exertion to adapt them to the distinct perception of objects. Hence in syncope as in sleep, as the power of volition is suspended, no external objects are perceived. See Sect. XVIII. 5. During the time which the patient lies in a fainting fit, the spirit of animation becomes accumulated; and hence the muscles in a while become irritable by their usual stimulation, and the fainting fit ceases. See Sect. XII. 7. 1.

7 . If the exertion of the voluntary motions has been still more energetic, the quiescence, which succeeds, is so complete, that they cannot again be excited into action by the efforts of the will. In this manner the palsy, and apoplexy (which is an universal palsy) are frequently produced after convulsions, or other violent exertions; of this I shall add a few instances.

Platernus mentions some, who have died apoplectic from violent exertions in dancing; and Dr. Mead, in his Essay on Poisons, records a patient in the hydrophobia, who at one effort broke the cords which bound him, and at the same instant expired. And it is probable, that those, who have expired from immoderate laughter, have died from this paralysis consequent to violent exertion. Mrs. Scott of Stafford was walking in her garden in perfect health with her neighbour Mrs. ——; the latter accidentally fell into a muddy rivulet, and tried in vain to disengage herself by the assistance of Mrs. Scott's hand. Mrs. Scott exerted her utmost power for many minutes, first to assist her friend, and next to prevent herself from being pulled into the morass, as her distressed companion would not disengage her hand. After other assistance was procured by their united screams, Mrs. Scott walked to a chair about twenty yards from the brook, and was seized with an apoplectic stroke: which continued many days, and terminated in a total loss of her right arm, and her speech; neither of which she ever after perfectly recovered.

It is said, that many people in Holland have died after skating too long or too violently on their frozen canals; it is probable the death of these, and of others, who have died suddenly in swimming, has been owing to this great quiescence or paralysis; which has succeeded very violent exertions, added to the concomitant cold, which has had greater effect after the sufferers had been heated and exhausted by previous exercise.

I remember a young man of the name of Nairne at Cambridge, who walking on the edge of a barge fell into the river. His cousin and fellow-student of the same name, knowing the other could not swim, plunged into the water after him, caught him by his clothes, and approaching the bank by a vehement exertion propelled him safe to the land, but that instant, seized, as was supposed, by the cramp, or paralysis, sunk to rise no more. The reason why the cramp of the muscles, which compose the calf of the leg, is so liable to affect swimmers, is, because these muscles have very weak antagonists, and are in walking generally elongated again after their contraction by the weight of the body on the ball of the toe, which is very much greater than the resistance of the water in swimming. See Section XVIII. 15.

It does not follow that every apoplectic or paralytic attack is immediately preceded by vehement exertion; the quiescence, which succeeds exertion, and which is not so great as to be termed paralysis, frequently recurs afterwards at certain periods; and by other causes of quiescence, occurring with those periods, as was explained in treating of the paroxysms of intermitting fevers; the quiescence at length, becomes so great as to be incapable of again being removed by the efforts of volition, and complete paralysis is formed. See Section XXXII. 3. 2.

Many of the paralytic patients, whom I have seen, have evidently had diseased livers from the too frequent potation of spirituous liquors; some of them have had the gutta rosea on their faces and breasts; which has in some degree receded either spontaneously, or by the use of external remedies, and the paralytic stroke has succeeded; and as in several persons, who have drank much vinous spirits, I have observed epileptic fits to commence at about forty or fifty years of age, without any hereditary taint, from the stimulus, as I believed, of a diseased liver; I was induced to ascribe many paralytic cases to the same source; which were not evidently the effect of age, or of unacquired debility. And the account given before of dropsies, which very frequently are owing to a paralysis of the absorbent system, and are generally attendant on free drinkers of spirituous liquors, confirmed me in this opinion.

The disagreeable irritation of a diseased liver produces exertions and consequent quiescence; these by the accidental concurrence of other causes of quiescence, as cold, solar or lunar periods, inanition, the want of their usual portion of spirit of wine, at length produces paralysis.

This is further confirmed by observing, that the muscles, we most frequently, or most powerfully exert, are most liable to palsy; as those of the voice and of articulation, and of those paralytics which I have seen, a much greater proportion have lost the use of their right arm; which is so much more generally exerted than the left.

I cannot dismiss this subject without observing, that after a paralytic stroke, if the vital powers are not much injured, that the patient has all the movements of the affected limb to learn over again, just as in early infancy; the limb is first moved by the irritation of its muscles, as in stretching, (of which a case was related in Section VII. 1. 3.) or by the electric concussion; afterwards it becomes obedient to sensation, as in violent danger or fear; and lastly, the muscles become again associated with volition, and gradually acquire their usual habits of acting together.

Another phænomenon in palsies is, that when the limbs of one side are disabled, those of the other are in perpetual motion. This can only be explained from conceiving that the power of motion, whatever it is, or wherever it resides, and which is capable of being exhausted by fatigue, and accumulated in rest, is now less expended, whilst one half of the body is capable of receiving its usual proportion of it, and is hence derived with greater ease or in greater abundance into the limbs, which remain unaffected.

II. 1 . The excess or defect of voluntary exertion produces similar effects upon the sensual motions, or ideas of the mind, as those already mentioned upon the muscular fibres. Thus when any violent pain, arising from the defect of some peculiar stimulus, exists either in the muscular or sensual systems of fibres, and which cannot be removed by acquiring the defective stimulus; as in some constitutions convulsions of the muscles are produced to procure a temporary relief, so in other constitutions vehement voluntary exertions of the ideas of the mind are produced for the same purpose; for during this exertion, like that of the muscles, the pain either vanishes or is diminished: this violent exertion constitutes madness; and in many cases I have seen the madness take place, and the convulsions cease, and reciprocally the madness cease, and the convulsions supervene. See Section III. 5. 8.

2 . Madness is distinguishable from delirium, as in the latter the patient knows not the place where he resides, nor the persons of his friends or attendants, nor is conscious of any external objects, except when spoken to with a louder voice, or stimulated with unusual force, and even then he soon relapses into a state of inattention to every thing about him. Whilst in the former he is perfectly sensible to every thing external, but has the voluntary powers of his mind intensely exerted on some particular object of his desire or aversion, he harbours in his thoughts a suspicion of all mankind, lest they should counteract his designs; and while he keeps his intentions, and the motives of his actions profoundly secret; he is perpetually studying the means of acquiring the object of his wish, or of preventing or revenging the injuries he suspects.

3 . A late French philosopher, Mr. Helvetius, has deduced almost all our actions from this principle of their relieving us from the ennui or tædium vitæ; and true it is, that our desires or aversions are the motives of all our voluntary actions; and human nature seems to excel other animals in the more facil use of this voluntary power, and on that account is more liable to insanity than other animals. But in mania this violent exertion of volition is expended on mistaken objects, and would not be relieved, though we were to gain or escape the objects, that excite it. Thus I have seen two instances of madmen, who conceived that they had the itch, and several have believed they had the venereal infection, without in reality having a symptom of either of them. They have been perpetually thinking upon this subject, and some of them were in vain salivated with design of convincing them to the contrary.

4 . In the minds of mad people those volitions alone exist, which are unmixed with sensation; immoderate suspicion is generally the first symptom, and want of shame, and want of delicacy about cleanliness. Suspicion is a voluntary exertion of the mind arising from the pain of fear, which it is exerted to relieve: shame is the name of a peculiar disagreeable sensation, see Fable of the Bees, and delicacy about cleanliness arises from another disagreeable sensation. And therefore are not found in the minds of maniacs, which are employed solely in voluntary exertions. Hence the most modest women in this disease walk naked amongst men without any kind of concern, use obscene discourse, and have no delicacy about their natural evacuations.

5 . Nor are maniacal people more attentive to their natural appetites, or to the irritations which surround them, except as far as may respect their suspicions or designs; for the violent and perpetual exertions of their voluntary powers of mind prevents their perception of almost every other object, either of irritation or of sensation. Hence it is that they bear cold, hunger, and fatigue, with much greater pertinacity than in their sober hours, and are less injured by them in respect to their general health. Thus it is asserted by historians, that Charles the Twelfth of Sweden slept on the snow, wrapped only in his cloak, at the siege of Frederickstad, and bore extremes of cold and hunger, and fatigue, under which numbers of his soldiers perished; because the king was insane with ambition, but the soldier had no such powerful stimulus to preserve his system from debility and death.

6 . Besides the insanities arising from exertions in consequence of pain, there is also a pleasurable insanity, as well as a pleasurable delirium; as the insanity of personal vanity, and that of religious fanaticism. When agreeable ideas excite into motion the sensorial power of sensation, and this again causes other trains of agreeable ideas, a constant stream of pleasurable ideas succeeds, and produces pleasurable delirium. So when the sensorial power of volition excites agreeable ideas, and the pleasure thus produced excites more volition in its turn, a constant flow of agreeable voluntary ideas succeeds; which when thus exerted in the extreme constitutes insanity.

Thus when our muscular actions are excited by our sensations of pleasure, it is termed play; when they are excited by our volition, it is termed work; and the former of these is attended with less fatigue, because the muscular actions in play produce in their turn more pleasurable sensation; which again has the property of producing more muscular action. An agreeable instance of this I saw this morning. A little boy, who was tired with walking, begged of his papa to carry him. "Here," says the reverend doctor, "ride upon my gold-headed cane;" and the pleased child, putting it between his legs, gallopped away with delight, and complained no more of his fatigue. Here the aid of another sensorial power, that of pleasurable sensation, superadded vigour to the exertion of exhausted volition. Which could otherwise only have been excited by additional pain, as by the lash of slavery. On this account where the whole sensorial power has been exerted on the contemplation of the promised joys of heaven, the saints of all persecuted religions have borne the tortures of martyrdom with otherwise unaccountable firmness.

7 . There are some diseases, which obtain at least a temporary relief from the exertions of insanity; many instances of dropsies being thus for a time cured are recorded. An elderly woman labouring with ascites I twice saw relieved for some weeks by insanity, the dropsy ceased for several weeks, and recurred again alternating with the insanity. A man afflicted with difficult respiration on lying down, with very irregular pulse, and œdematous legs, whom I saw this day, has for above a week been much relieved in respect to all those symptoms by the accession of insanity, which is shewn by inordinate suspicion, and great anger.

In cases of common temporary anger the increased action of the arterial system is seen by the red skin, and increased pulse, with the immediate increase of muscular activity. A friend of mine, when he was painfully fatigued by riding on horseback, was accustomed to call up ideas into his mind, which used to excite his anger or indignation, and thus for a time at least relieved the pain of fatigue. By this temporary insanity, the effect of the voluntary power upon the whole of his system was increased; as in the cases of dropsy above mentioned, it would appear, that the increased action of the voluntary faculty of the sensorium affected the absorbent system, as well as the secerning one.

8 . In respect to relieving inflammatory pains, and removing fever, I have seen many instances, as mentioned in Sect. XII. 2. 4. One lady, whom I attended, had twice at some years interval a locked jaw, which relieved a pain on her sternum with peripneumony. Two other ladies I saw, who towards the end of violent peripneumony, in which they frequently lost blood, were at length cured by insanity supervening. In the former the increased voluntary exertion of the muscles of the jaw, in the latter that of the organs of sense, removed the disease; that is, the disagreeable sensation, which had produced the inflammation, now excited the voluntary power, and these new voluntary exertions employed or expended the superabundant sensorial power, which had previously been exerted on the arterial system, and caused inflammation.

Another case, which I think worth relating, was of a young man about twenty; he had laboured under an irritative fever with debility for three or four weeks, with very quick and very feeble pulse, and other usual symptoms of that species of typhus, but at this time complained much and frequently of pain of his legs and feet. When those who attended him were nearly in despair of his recovery, I observed with pleasure an insanity of mind supervene: which was totally different from delirium, as he knew his friends, calling them by their names, and the room in which he lay, but became violently suspicious of his attendants, and calumniated with vehement oaths his tender mother, who sat weeping by his bed. On this his pulse became slower and firmer, but the quickness did not for some time intirely cease, and he gradually recovered. In this case the introduction of an increased quantity of the power of volition gave vigour to those movements of the system, which are generally only actuated by the power of irritation, and of association.

Another case I recollect of a young man, about twenty-five, who had the scarlet-fever, with very quick pulse, and an universal eruption on his skin, and was not without reason esteemed to be in great danger of his life. After a few days an insanity supervened, which his friends mistook for delirium, and he gradually recovered, and the cuticle peeled off. From these and a few other cases I have always esteemed insanity to be a favourable sign in fevers, and have cautiously distinguished it from delirium.

III. Another mode of mental exertion to relieve pain, is by producing a train of ideas not only by the efforts of volition, as in insanity; but by those of sensation likewise, as in delirium and sleep. This mental effort is termed reverie, or somnambulation, and is described more at large in Sect. XIX. on that subject. But I shall here relate another case of that wonderful disease, which fell yesterday under my eye, and to which I have seen many analogous alienations of mind, though not exactly similar in all circumstances. But as all of them either began or terminated with pain or convulsion, there can be no doubt but that they are of epileptic origin, and constitute another mode of mental exertion to relieve some painful sensation.

1 . Master A. about nine years old, had been seized at seven every morning for ten days with uncommon fits, and had had slight returns in the afternoon. They were supposed to originate from worms, and had been in vain attempted to be removed by vermifuge purges. As his fit was expected at seven yesterday morning, I saw him before that hour; he was asleep, seemed free from pain, and his pulse natural. About seven he began to complain of pain about his navel, or more to the left side, and in a few minutes had exertions of his arms and legs like swimming. He then for half an hour hunted a pack of hounds; as appeared by his hallooing, and calling the dogs by their names, and discoursing with the attendants of the chase, describing exactly a day of hunting, which (I was informed) he had witnessed a year before, going through all the most minute circumstances of it; calling to people, who were then present, and lamenting the absence of others, who were then also absent. After this scene he imitated, as he lay in bed, some of the plays of boys, as swimming and jumping. He then sung an English and then an Italian song; part of which with his eyes open, and part with them closed, but could not be awakened or excited by any violence, which it was proper to use.

After about an hour he came suddenly to himself with apparent surprise, and seemed quite ignorant of any part of what had passed, and after being apparently well for half an hour, he suddenly fell into a great stupor, with slower pulse than natural, and a slow moaning respiration, in which he continued about another half hour, and then recovered.

The sequel of this disease was favourable; he was directed one grain of opium at six every morning, and then to rise out of bed; at half past six he was directed fifteen drops of laudanum in a glass of wine and water. The first day the paroxysm became shorter, and less violent. The dose of opium was increased to one-half more, and in three or four days the fits left him. The bark and filings of iron were also exhibited twice a day; and I believe the complaint returned no more.

2 . In this paroxysm it must be observed, that he began with pain, and ended with stupor, in both circumstances resembling a fit of epilepsy. And that therefore the exertions both of mind and body, both the voluntary ones, and those immediately excited by pleasurable sensation, were exertions to relieve pain.

The hunting scene appeared to be rather an act of memory than of imagination, and was therefore rather a voluntary exertion, though attended with the pleasurable eagerness, which was the consequence of those ideas recalled by recollection, and not the cause of them.

These ideas thus voluntarily recollected were succeeded by sensations of pleasure, though his senses were unaffected by the stimuli of visible or audible objects; or so weakly excited by them as not to produce sensation or attention. And the pleasure thus excited by volition produced other ideas and other motions in consequence of the sensorial power of sensation. Whence the mixed catenations of voluntary and sensitive ideas and muscular motions in reverie; which, like every other kind of vehement exertion, contribute to relieve pain, by expending a large quantity of sensorial power.

Those fits generally commence during sleep, from whence I suppose they have been thought to have some connection with sleep, and have thence been termed Somnambulism; but their commencement during sleep is owing to our increased excitability by internal sensations at that time, as explained in Sect. XVIII. 14. and 15., and not to any similitude between reverie and sleep.

3 . I was once concerned for a very elegant and ingenious young lady, who had a reverie on alternate days, which continued nearly the whole day; and as in her days of disease she took up the same kind of ideas, which she had conversed about on the alternate day before, and could recollect nothing of them on her well-day; she appeared to her friends to possess two minds. This case also was of epileptic kind, and was cured, with some relapses, by opium administered before the commencement of the paroxysm.

4 . Whence it appears, that the methods of relieving inflammatory pains, is by removing all stimulus, as by venesection, cool air, mucilaginous diet, aqueous potation, silence, darkness.

The methods of relieving pains from defect of stimulus is by supplying the peculiar stimulus required, as of food, or warmth.

And the general method of relieving pain is by exciting into action some great part of the system for the purpose of expending a part of the sensorial power. This is done either by exertion of the voluntary ideas and muscles, as in insanity and convulsion; or by exerting both voluntary and sensitive motions, as in reverie; or by exciting the irritative motions by wine or opium internally, and by the warm bath or blisters externally; or lastly, by exciting the sensitive ideas by good news, affecting stories, or agreeable passions.

title: Zoonomia/I.XXXIV