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Cell wall

A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. While absent in many eukaryotes, including animals, cell walls are prevalent in other organisms such as fungi, algae and plants, and are commonly found in most prokaryotes, with the exception of mollicute bacteria.

The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In land plants, the primary cell wall comprises polysaccharides like cellulose, hemicelluloses, and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit cell walls composed of glycoproteins and polysaccharides, such as carrageenan and agar, distinct from those in land plants. Bacterial cell walls contain peptidoglycan, while archaeal cell walls vary in composition, potentially consisting of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls constructed from the polymer chitin, specifically N-acetylglucosamine. Interestingly, diatoms have a unique cell wall composed of biogenic silica.

History
A plant cell wall was first observed and named (simply as a "wall") by Robert Hooke in 1665. However, "the dead excrusion product of the living protoplast" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.

In 1804, Karl Rudolphi and J.H.F. Link proved that cells had independent cell walls. Before, it had been thought that cells shared walls and that fluid passed between them this way.

The mode of formation of the cell wall was controversial in the 19th century. Hugo von Mohl (1853, 1858) advocated the idea that the cell wall grows by apposition. Carl Nägeli (1858, 1862, 1863) believed that the growth of the wall in thickness and in area was due to a process termed intussusception. Each theory was improved in the following decades: the apposition (or lamination) theory by Eduard Strasburger (1882, 1889), and the intussusception theory by Julius Wiesner (1886).

In 1930, Ernst Münch coined the term apoplast in order to separate the "living" symplast from the "dead" plant region, the latter of which included the cell wall.

By the 1980s, some authors suggested replacing the term "cell wall", particularly as it was used for plants, with the more precise term "extracellular matrix", as used for animal cells, but others preferred the older term.

Properties
Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. In multicellular organisms, they permit the organism to build and hold a definite shape. Cell walls also limit the entry of large molecules that may be toxic to the cell. They further permit the creation of stable osmotic environments by preventing osmotic lysis and helping to retain water. Their composition, properties, and form may change during the cell cycle and depend on growth conditions.

Rigidity of cell walls
In most cells, the cell wall is flexible, meaning that it will bend rather than holding a fixed shape, but has considerable tensile strength. The apparent rigidity of primary plant tissues is enabled by cell walls, but is not due to the walls' stiffness. Hydraulic turgor pressure creates this rigidity, along with the wall structure. The flexibility of the cell walls is seen when plants wilt, so that the stems and leaves begin to droop, or in seaweeds that bend in water currents. As John Howland explains

"Think of the cell wall as a wicker basket in which a balloon has been inflated so that it exerts pressure from the inside. Such a basket is very rigid and resistant to mechanical damage. Thus does the prokaryote cell (and eukaryotic cell that possesses a cell wall) gain strength from a flexible plasma membrane pressing against a rigid cell wall."

The apparent rigidity of the cell wall thus results from inflation of the cell contained within. This inflation is a result of the passive uptake of water.

In plants, a secondary cell wall is a thicker additional layer of cellulose which increases wall rigidity. Additional layers may be formed by lignin in xylem cell walls, or suberin in cork cell walls. These compounds are rigid and waterproof, making the secondary wall stiff. Both wood and bark cells of trees have secondary walls. Other parts of plants such as the leaf stalk may acquire similar reinforcement to resist the strain of physical forces.

Permeability
The primary cell wall of most plant cells is freely permeable to small molecules including small proteins, with size exclusion estimated to be 30-60 kDa. The pH is an important factor governing the transport of molecules through cell walls.

Evolution
Cell walls evolved independently in many groups.

The photosynthetic eukaryotes (so-called plant and algae) is one group with cellulose cell walls, where the cell wall is closely related to the evolution of multicellularity, terrestrialization and vascularization. The CesA cellulose synthase evolved in Cyanobacteria and was part of Archaeplastida since endosymbiosis; secondary endosymbiosis events transferred it (with the arabinogalactan proteins) further into brown algae and oomycetes. Plants later evolved various genes from CesA, including the Csl (cellulose synthase-like) family of proteins and additional Ces proteins. Combined with the various glycosyltransferases (GT), they enable more complex chemical structures to be built.

Fungi use a chitin-glucan-protein cell wall. They share the 1,3-β-glucan synthesis pathway with plants, using homologous GT48 family 1,3-Beta-glucan synthases to perform the task, suggesting that such an enzyme is very ancient within the eukaryotes. Their glycoproteins are rich in mannose. The cell wall might have evolved to deter viral infections. Proteins embedded in cell walls are variable, contained in tandem repeats subject to homologous recombination. An alternative scenario is that fungi started with a chitin-based cell wall and later acquired the GT-48 enzymes for the 1,3-β-glucans via horizontal gene transfer. The pathway leading to 1,6-β-glucan synthesis is not sufficiently known in either case.

Plant cell walls
The walls of plant cells must have sufficient tensile strength to withstand internal osmotic pressures of several times atmospheric pressure that result from the difference in solute concentration between the cell interior and external solutions. Plant cell walls vary from 0.1 to several μm in thickness.

Layers

Up to three strata or layers may be found in plant cell walls:

 * The primary cell wall, generally a thin, flexible and extensible layer formed while the cell is growing.
 * The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. Some cells, such as the conducting cells in xylem, possess a secondary wall containing lignin, which strengthens and waterproofs the wall.
 * The middle lamella, a layer rich in pectins. This outermost layer forms the interface between adjacent plant cells and glues them together.

Composition
In the primary (growing) plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix. The most common hemicellulose in the primary cell wall is xyloglucan. In grass cell walls, xyloglucan and pectin are reduced in abundance and partially replaced by glucuronoarabinoxylan, another type of hemicellulose. Primary cell walls characteristically extend (grow) by a mechanism called acid growth, mediated by expansins, extracellular proteins activated by acidic conditions that modify the hydrogen bonds between pectin and cellulose. This functions to increase cell wall extensibility. The outer part of the primary cell wall of the plant epidermis is usually impregnated with cutin and wax, forming a permeability barrier known as the plant cuticle.

Secondary cell walls contain a wide range of additional compounds that modify their mechanical properties and permeability. The major polymers that make up wood (largely secondary cell walls) include:
 * cellulose, 35-50%
 * xylan, 20-35%, a type of hemicellulose
 * lignin, 10-25%, a complex phenolic polymer that penetrates the spaces in the cell wall between cellulose, hemicellulose and pectin components, driving out water and strengthening the wall.

Additionally, structural proteins (1-5%) are found in most plant cell walls; they are classified as hydroxyproline-rich glycoproteins (HRGP), arabinogalactan proteins (AGP), glycine-rich proteins (GRPs), and proline-rich proteins (PRPs). Each class of glycoprotein is defined by a characteristic, highly repetitive protein sequence. Most are glycosylated, contain hydroxyproline (Hyp) and become cross-linked in the cell wall. These proteins are often concentrated in specialized cells and in cell corners. Cell walls of the epidermis may contain cutin. The Casparian strip in the endodermis roots and cork cells of plant bark contain suberin. Both cutin and suberin are polyesters that function as permeability barriers to the movement of water. The relative composition of carbohydrates, secondary compounds and proteins varies between plants and between the cell type and age. Plant cells walls also contain numerous enzymes, such as hydrolases, esterases, peroxidases, and transglycosylases, that cut, trim and cross-link wall polymers.

Secondary walls - especially in grasses - may also contain microscopic silica crystals, which may strengthen the wall and protect it from herbivores.

Cell walls in some plant tissues also function as storage deposits for carbohydrates that can be broken down and resorbed to supply the metabolic and growth needs of the plant. For example, endosperm cell walls in the seeds of cereal grasses, nasturtium and other species, are rich in glucans and other polysaccharides that are readily digested by enzymes during seed germination to form simple sugars that nourish the growing embryo.

Formation
The middle lamella is laid down first, formed from the cell plate during cytokinesis, and the primary cell wall is then deposited inside the middle lamella. The actual structure of the cell wall is not clearly defined and several models exist - the covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model. However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles. Cellulose microfibrils are produced at the plasma membrane by the cellulose synthase complex, which is proposed to be made of a hexameric rosette that contains three cellulose synthase catalytic subunits for each of the six units. Microfibrils are held together by hydrogen bonds to provide a high tensile strength. The cells are held together and share the gelatinous membrane (the middle lamella), which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesmata, which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall.

In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plasma membrane and primary wall. Unlike the primary wall, the cellulose microfibrils are aligned parallel in layers, the orientation changing slightly with each additional layer so that the structure becomes helicoidal. Cells with secondary cell walls can be rigid, as in the gritty sclereid cells in pear and quince fruit. Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesmata to connect cells through the secondary cell walls.

Fungal cell walls
There are several groups of organisms that have been called "fungi". Some of these groups (Oomycete and Myxogastria) have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall. Most true fungi have a cell wall consisting largely of chitin and other polysaccharides. True fungi do not have cellulose in their cell walls.

In fungi, the cell wall is the outer-most layer, external to the plasma membrane. The fungal cell wall is a matrix of three main components:
 * chitin: polymers consisting mainly of unbranched chains of β-(1,4)-linked-N-Acetylglucosamine in the Ascomycota and Basidiomycota, or poly-β-(1,4)-linked-N-Acetylglucosamine (chitosan) in the Zygomycota. Both chitin and chitosan are synthesized and extruded at the plasma membrane.
 * glucans: glucose polymers that function to cross-link chitin or chitosan polymers. β-glucans are glucose molecules linked via β-(1,3)- or β-(1,6)- bonds and provide rigidity to the cell wall while α-glucans are defined by α-(1,3)- and/or α-(1,4) bonds and function as part of the matrix.
 * proteins: enzymes necessary for cell wall synthesis and lysis in addition to structural proteins are all present in the cell wall. Most of the structural proteins found in the cell wall are glycosylated and contain mannose, thus these proteins are called mannoproteins or mannans.

Algae
Like plants, algae have cell walls. Algal cell walls contain either polysaccharides (such as cellulose (a glucan)) or a variety of glycoproteins (Volvocales) or both. The inclusion of additional polysaccharides in algal cells walls is used as a feature for algal taxonomy.

 * Mannans: They form microfibrils in the cell walls of a number of marine green algae including those from the genera, Codium, Dasycladus, and Acetabularia as well as in the walls of some red algae, like Porphyra and Bangia.
 * Xylans:
 * Alginic acid: It is a common polysaccharide in the cell walls of brown algae.
 * Sulfonated polysaccharides: They occur in the cell walls of most algae; those common in red algae include agarose, carrageenan, porphyran, furcelleran and funoran.

Other compounds that may accumulate in algal cell walls include sporopollenin and calcium ions.

The group of algae known as the diatoms synthesize their cell walls (also known as frustules or valves) from silicic acid. Significantly, relative to the organic cell walls produced by other groups, silica frustules require less energy to synthesize (approximately 8%), potentially a major saving on the overall cell energy budget and possibly an explanation for higher growth rates in diatoms.

In brown algae, phlorotannins may be a constituent of the cell walls.

Water molds
The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as Achlya and Saprolegnia) do have chitin in their walls. The fraction of cellulose in the walls is no more than 4 to 20%, far less than the fraction of glucans. Oomycete cell walls also contain the amino acid hydroxyproline, which is not found in fungal cell walls.

Slime molds
The dictyostelids are another group formerly classified among the fungi. They are slime molds that feed as unicellular amoebae, but aggregate into a reproductive stalk and sporangium under certain conditions. Cells of the reproductive stalk, as well as the spores formed at the apex, possess a cellulose wall. The spore wall has three layers, the middle one composed primarily of cellulose, while the innermost is sensitive to cellulase and pronase.

Bacterial cell walls

Around the outside of the cell membrane is the bacterial cell wall. Bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, although L-form bacteria can be produced in the laboratory that lack a cell wall. The antibiotic penicillin is able to kill bacteria by preventing the cross-linking of peptidoglycan and this causes the cell wall to weaken and lyse. The lysozyme enzyme can also damage bacterial cell walls.

There are broadly speaking two different types of cell wall in bacteria, called gram-positive and gram-negative. The names originate from the reaction of cells to the Gram stain, a test long-employed for the classification of bacterial species.

Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids.

Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Most bacteria have the gram-negative cell wall and only the Bacillota and Actinomycetota (previously known as the low G+C and high G+C gram-positive bacteria, respectively) have the alternative gram-positive arrangement.

These differences in structure produce differences in antibiotic susceptibility. The beta-lactam antibiotics (e.g. penicillin, cephalosporin) only work against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. The glycopeptide antibiotics (e.g. vancomycin, teicoplanin, telavancin) only work against gram-positive pathogens such as Staphylococcus aureus

Archaeal cell walls
Although not truly unique, the cell walls of Archaea are unusual. Whereas peptidoglycan is a standard component of all bacterial cell walls, all archaeal cell walls lack peptidoglycan, though some methanogens have a cell wall made of a similar polymer called pseudopeptidoglycan. There are four types of cell wall currently known among the Archaea.

One type of archaeal cell wall is that composed of pseudopeptidoglycan (also called pseudomurein). This type of wall is found in some methanogens, such as Methanobacterium and Methanothermus. While the overall structure of archaeal pseudopeptidoglycan superficially resembles that of bacterial peptidoglycan, there are a number of significant chemical differences. Like the peptidoglycan found in bacterial cell walls, pseudopeptidoglycan consists of polymer chains of glycan cross-linked by short peptide connections. However, unlike peptidoglycan, the sugar N-acetylmuramic acid is replaced by N-acetyltalosaminuronic acid, and the two sugars are bonded with a β,1-3 glycosidic linkage instead of β,1-4. Additionally, the cross-linking peptides are L-amino acids rather than D-amino acids as they are in bacteria.

A second type of archaeal cell wall is found in Methanosarcina and Halococcus. This type of cell wall is composed entirely of a thick layer of polysaccharides, which may be sulfated in the case of Halococcus. Structure in this type of wall is complex and not fully investigated.

A third type of wall among the Archaea consists of glycoprotein, and occurs in the hyperthermophiles, Halobacterium, and some methanogens. In Halobacterium, the proteins in the wall have a high content of acidic amino acids, giving the wall an overall negative charge. The result is an unstable structure that is stabilized by the presence of large quantities of positive sodium ions that neutralize the charge. Consequently, Halobacterium thrives only under conditions with high salinity.

In other Archaea, such as Methanomicrobium and Desulfurococcus, the wall may be composed only of surface-layer proteins, known as an S-layer. S-layers are common in bacteria, where they serve as either the sole cell-wall component or an outer layer in conjunction with polysaccharides. Most Archaea are Gram-negative, though at least one Gram-positive member is known.

Other cell coverings
Many protists and bacteria produce other cell surface structures apart from cell walls, external (extracellular matrix) or internal. Many algae have a sheath or envelope of mucilage outside the cell made of exopolysaccharides. Diatoms build a frustule from silica extracted from the surrounding water; radiolarians, foraminiferans, testate amoebae and silicoflagellates also produce a skeleton from minerals, called test in some groups. Many green algae, such as Halimeda and the Dasycladales, and some red algae, the Corallinales, encase their cells in a secreted skeleton of calcium carbonate. In each case, the wall is rigid and essentially inorganic. It is the non-living component of cell. Some golden algae, ciliates and choanoflagellates produces a shell-like protective outer covering called lorica. Some dinoflagellates have a theca of cellulose plates, and coccolithophorids have coccoliths.

An extracellular matrix (ECM) is also present in metazoans. Its composition varies between cells, but collagens are the most abundant protein in the ECM.

title: Cell wall


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Classical element

The classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Angola, Tibet, India, and Mali had similar lists which sometimes referred, in local languages, to "air" as "wind", and to "aether" as "space".

These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism (the idea of very small, indivisible portions of matter), but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature.

While the classification of the material world in ancient India, Hellenistic Egypt, and ancient Greece into air, earth, fire, and water was more philosophical, during the Middle Ages medieval scientists used practical, experimental observation to classify materials. In Europe, the ancient Greek concept, devised by Empedocles, evolved into the systematic classifications of Aristotle and Hippocrates. This evolved slightly into the medieval system, and eventually became the object of experimental verification in the 17th century, at the start of the Scientific Revolution.

Modern science does not support the classical elements to classify types of substances. Atomic theory classifies atoms into more than a hundred chemical elements such as oxygen, iron, and mercury, which may form chemical compounds and mixtures. The modern categories roughly corresponding to the classical elements are the states of matter produced under different temperatures and pressures. Solid, liquid, gas, and plasma share many attributes with the corresponding classical elements of earth, water, air, and fire, but these states describe the similar behavior of different types of atoms at similar energy levels, not the characteristic behavior of certain atoms or substances.

Hellenistic philosophy
The ancient Greek concept of four basic elements, these being earth (γῆ ), water (ὕδωρ ), air (ἀήρ ), and fire (πῦρ ), dates from pre-Socratic times and persisted throughout the Middle Ages and into the Early modern period, deeply influencing European thought and culture.

Water, air, or fire?
The classical elements were first proposed independently by several early Pre-Socratic philosophers. Greek philosophers had debated which substance was the arche ("first principle"), or primordial element from which everything else was made. Thales (c. 626/623) believed that water was this principle. Anaximander (c. 610) argued that the primordial substance was not any of the known substances, but could be transformed into them, and they into each other. Anaximenes (c. 586) favored air, and Heraclitus ( fl.  c. 500 BC) championed fire.

Fire, earth, air, and water
The Greek philosopher Empedocles (c. 450 BC) was the first to propose the four classical elements as a set: fire, earth, air, and water. He called them the four "roots" (ῥιζώματα, ). Empedocles also proved (at least to his own satisfaction) that air was a separate substance by observing that a bucket inverted in water did not become filled with water, a pocket of air remaining trapped inside.

Fire, earth, air, and water have become the most popular set of classical elements in modern interpretations. One such version was provided by Robert Boyle in The Sceptical Chymist, which was published in 1661 in the form of a dialogue between five characters. Themistius, the Aristotelian of the party, says:

"If You but consider a piece of green-Wood burning in a Chimney, You will readily discern in the disbanded parts of it the four Elements, of which we teach It and other mixt bodies to be compos’d. The fire discovers it self in the flame ... the smoke by ascending to the top of the chimney, and there readily vanishing into air ... manifests to what Element it belongs and gladly returnes. The water ... boyling and hissing at the ends of the burning Wood betrayes it self ... and the ashes by their weight, their firiness, and their dryness, put it past doubt that they belong to the Element of Earth."

Humorism (Hippocrates)
According to Galen, these elements were used by Hippocrates (c. 460) in describing the human body with an association with the four humours: yellow bile (fire), black bile (earth), blood (air), and phlegm (water). Medical care was primarily about helping the patient stay in or return to their own personal natural balanced state.

Plato
Plato (428/423 – 348/347 BC) seems to have been the first to use the term "element (στοιχεῖον, )" in reference to air, fire, earth, and water. The ancient Greek word for element, (from, "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed.

Aristotle
In On the Heavens (350 BC), Aristotle defines "element" in general: "An element, we take it, is a body into which other bodies may be analysed, present in them potentially or in actuality (which of these, is still disputable), and not itself divisible into bodies different in form. That, or something like it, is what all men in every case mean by element."

In his On Generation and Corruption, Aristotle related each of the four elements to two of the four sensible qualities:
 * Fire is both hot and dry.
 * Air is both hot and wet (for air is like vapor, ἀτμὶς).
 * Water is both cold and wet.
 * Earth is both cold and dry.

A classic diagram has one square inscribed in the other, with the corners of one being the classical elements, and the corners of the other being the properties. The opposite corner is the opposite of these properties, "hot – cold" and "dry – wet".

Aether
Aristotle added a fifth element, aether (αἰθήρ ), as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly substance. It had previously been believed by pre-Socratics such as Empedocles and Anaxagoras that aether, the name applied to the material of heavenly bodies, was a form of fire. Aristotle himself did not use the term aether for the fifth element, and strongly criticised the pre-Socratics for associating the term with fire. He preferred a number of other terms indicating eternal movement, thus emphasising the evidence for his discovery of a new element. These five elements have been associated since Plato's Timaeus with the five platonic solids.

Neo-Platonism
The Neoplatonic philosopher Proclus rejected Aristotle's theory relating the elements to the sensible qualities hot, cold, wet, and dry. He maintained that each of the elements has three properties. Fire is sharp (ὀξυτητα), subtle (λεπτομερειαν), and mobile (εὐκινησιαν) while its opposite, earth, is blunt (αμβλυτητα), dense (παχυμερειαν), and immobile (ακινησιαν ); they are joined by the intermediate elements, air and water, in the following fashion:

Hermeticism
A text written in Egypt in Hellenistic or Roman times called the Kore Kosmou ("Virgin of the World") ascribed to Hermes Trismegistus (associated with the Egyptian god Thoth), names the four elements fire, water, air, and earth. As described in this book:

"And Isis answer made: Of living things, my son, some are made friends with fire, and some with water, some with air, and some with earth, and some with two or three of these, and some with all. And, on the contrary, again some are made enemies of fire, and some of water, some of earth, and some of air, and some of two of them, and some of three, and some of all. For instance, son, the locust and all flies flee fire; the eagle and the hawk and all high-flying birds flee water; fish, air and earth; the snake avoids the open air. Whereas snakes and all creeping things love earth; all swimming things love water; winged things, air, of which they are the citizens; while those that fly still higher love the fire and have the habitat near it. Not that some of the animals as well do not love fire; for instance salamanders, for they even have their homes in it. It is because one or another of the elements doth form their bodies' outer envelope. Each soul, accordingly, while it is in its body is weighted and constricted by these four."

Hinduism
The system of five elements are found in Vedas, especially Ayurveda, the pancha mahabhuta, or "five great elements", of Hinduism are: They further suggest that all of creation, including the human body, is made of these five essential elements and that upon death, the human body dissolves into these five elements of nature, thereby balancing the cycle of nature.
 * 1) bhūmi or pṛthvī (earth),
 * 2) āpas or jala (water),
 * 3) agní or tejas (fire),
 * 4) vāyu, vyāna, or vāta (air or wind)
 * 5) ākāśa, vyom, or śūnya (space or zero) or (aether or void).

The five elements are associated with the five senses, and act as the gross medium for the experience of sensations. The basest element, earth, created using all the other elements, can be perceived by all five senses — (i) hearing, (ii) touch, (iii) sight, (iv) taste, and (v) smell. The next higher element, water, has no odor but can be heard, felt, seen and tasted. Next comes fire, which can be heard, felt and seen. Air can be heard and felt. "Akasha" (aether) is beyond the senses of smell, taste, sight, and touch; it being accessible to the sense of hearing alone.

Buddhism
Buddhism has had a variety of thought about the five elements and their existence and relevance, some of which continue to this day.

In the Pali literature, the mahabhuta ("great elements") or catudhatu ("four elements") are earth, water, fire and air. In early Buddhism, the four elements are a basis for understanding suffering and for liberating oneself from suffering. The earliest Buddhist texts explain that the four primary material elements are solidity, fluidity, temperature, and mobility, characterized as earth, water, fire, and air, respectively.

The Buddha's teaching regarding the four elements is to be understood as the base of all observation of real sensations rather than as a philosophy. The four properties are cohesion (water), solidity or inertia (earth), expansion or vibration (air) and heat or energy content (fire). He promulgated a categorization of mind and matter as composed of eight types of "kalapas" of which the four elements are primary and a secondary group of four are colour, smell, taste, and nutriment which are derivative from the four primaries.

Thanissaro Bhikkhu (1997) renders an extract of Shakyamuni Buddha's from Pali into English thus: "Just as a skilled butcher or his apprentice, having killed a cow, would sit at a crossroads cutting it up into pieces, the monk contemplates this very body — however it stands, however it is disposed — in terms of properties: 'In this body there is the earth property, the liquid property, the fire property, & the wind property.'"

Tibetan Buddhist medical literature speaks of the (five elements) or "elemental properties": earth, water, fire, wind, and space. The concept was extensively used in traditional Tibetan medicine. Tibetan Buddhist theology, tantra traditions, and "astrological texts" also spoke of them making up the "environment, [human] bodies," and at the smallest or "subtlest" level of existence, parts of thought and the mind. Also at the subtlest level of existence, the elements exist as "pure natures represented by the five female buddhas", Ākāśadhātviśvarī, Buddhalocanā, Mamakī, Pāṇḍarāvasinī, and Samayatārā, and these pure natures "manifest as the physical properties of earth (solidity), water (fluidity), fire (heat and light), wind (movement and energy), and" the expanse of space. These natures exist as all "qualities" that are in the physical world and take forms in it.

Angola
In traditional Bakongo religion, the five elements are incorporated into the Kongo cosmogram. This sacred symbol also depicts the physical world (Nseke), the spiritual world of the ancestors (Mpémba), the Kalûnga line that runs between the two worlds, the circular void that originally formed the two worlds (mbûngi), and the path of the sun. Each element correlates to a period in the life cycle, which the Bakongo people also equate to the four cardinal directions. According to their cosmology, all living things go through this cycle.

 * Aether represents mbûngi, the circular void that begot the universe.
 * Air (South) represents musoni, the period of conception that takes place during spring.
 * Fire (East) represent kala, the period of birth that takes place during summer.
 * Earth (North) represents tukula, the period of maturity that takes place during fall.
 * Water (West) represents luvemba, the period of death that takes place during winter

Mali
In traditional Bambara spirituality, the Supreme God created four additional essences of himself during creation. Together, these five essences of the deity correlate with the five classical elements.

 * Koni is the thought and void (aether).
 * Bemba (also called Pemba) is the god of the sky and air.
 * Nyale (also called Koroni Koundyé) is the goddess of fire.
 * Faro is the androgynous god of water.
 * Ndomadyiri is the god and master of the earth.

Alchemy

The elemental system used in medieval alchemy was developed primarily by the anonymous authors of the Arabic works attributed to Pseudo Apollonius of Tyana. This system consisted of the four classical elements of air, earth, fire, and water, in addition to a new theory called the sulphur-mercury theory of metals, which was based on two elements: sulphur, characterizing the principle of combustibility, "the stone which burns"; and mercury, characterizing the principle of metallic properties. They were seen by early alchemists as idealized expressions of irreducible components of the universe and are of larger consideration within philosophical alchemy.

The three metallic principles—sulphur to flammability or combustion, mercury to volatility and stability, and salt to solidity—became the tria prima of the Swiss alchemist Paracelsus. He reasoned that Aristotle's four element theory appeared in bodies as three principles. Paracelsus saw these principles as fundamental and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke described the volatility (the mercurial principle), the heat-giving flames described flammability (sulphur), and the remnant ash described solidity (salt).

Japan
Japanese traditions use a set of elements called the 五大 (godai, literally "five great"). These five are earth, water, fire, wind/air, and void. These came from Indian Vastu shastra philosophy and Buddhist beliefs; in addition, the classical Chinese elements (五行, wu xing) are also prominent in Japanese culture, especially to the influential Neo-Confucianists during the medieval Edo period.

 * Earth represented rocks and stability.
 * Water represented fluidity and adaptability.
 * Fire represented life and energy.
 * Wind represented movement and expansion.
 * Void or Sky/Heaven represented spirit and creative energy.

Medieval Aristotelian philosophy
The Islamic philosophers al-Kindi, Avicenna and Fakhr al-Din al-Razi followed Aristotle in connecting the four elements with the four natures heat and cold (the active force), and dryness and moisture (the recipients).

Medicine Wheel
The medicine wheel symbol is a modern invention attributed to Native American peoples dating to approximately 1972, with the following descriptions and associations being a later addition. The associations with the classical elements are not grounded in traditional Indigenous teachings and the symbol has not been adopted by all Indigenous American nations.

 * Earth (South) represents the youth cycle, summer, the Indigenous race, and cedar medicine.
 * Fire (East) represents the birth cycle, spring, the Asian race, and tobacco medicine.
 * Wind/Air (North) represents the elder cycle, winter, the European race, and sweetgrass medicine.
 * Water (West) represents the adulthood cycle, autumn, the African race, and sage medicine.

Chemical element
The Aristotelian tradition and medieval alchemy eventually gave rise to modern chemistry, scientific theories and new taxonomies. By the time of Antoine Lavoisier, for example, a list of elements would no longer refer to classical elements. Some modern scientists see a parallel between the classical elements and the four states of matter: solid, liquid, gas and weakly ionized plasma.

Modern science recognizes classes of elementary particles which have no substructure (or rather, particles that are not made of other particles) and composite particles having substructure (particles made of other particles).

Western astrology
Western astrology uses the four classical elements in connection with astrological charts and horoscopes. The twelve signs of the zodiac are divided into the four elements: Fire signs are Aries, Leo and Sagittarius, Earth signs are Taurus, Virgo and Capricorn, Air signs are Gemini, Libra and Aquarius, and Water signs are Cancer, Scorpio, and Pisces.

Criticism
The Dutch historian of science Eduard Jan Dijksterhuis writes that the theory of the classical elements "was bound to exercise a really harmful influence. As is now clear, Aristotle, by adopting this theory as the basis of his interpretation of nature and by never losing faith in it, took a course which promised few opportunities and many dangers for science." Bertrand Russell says that Aristotle's thinking became imbued with almost biblical authority in later centuries. So much so that "Ever since the beginning of the seventeenth century, almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine".

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

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Fire (classical element)

Fire is one of the four classical elements along with earth, water and air in ancient Greek philosophy and science. Fire is considered to be both hot and dry and, according to Plato, is associated with the tetrahedron.

Greek and Roman tradition
Fire is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with the qualities of energy, assertiveness, and passion. In one Greek myth, Prometheus stole fire from the gods to protect the otherwise helpless humans, but was punished for this charity.

Fire was one of many archai proposed by the pre-Socratics, most of whom sought to reduce the cosmos, or its creation, to a single substance. Heraclitus (c. 535 BCE – c. 475 BCE) considered fire to be the most fundamental of all elements. He believed fire gave rise to the other three elements: "All things are an interchange for fire, and fire for all things, just like goods for gold and gold for goods." He had a reputation for obscure philosophical principles and for speaking in riddles. He described how fire gave rise to the other elements as the: "upward-downward path", (ὁδὸς ἄνω κάτω), a "hidden harmony"  or series of transformations he called the "turnings of fire", (πυρὸς τροπαὶ), first into sea, and half that sea into earth, and half that earth into rarefied air. This is a concept that anticipates both the four classical elements of Empedocles and Aristotle's transmutation of the four elements into one another. "This world, which is the same for all, no one of gods or men has made. But it always was and will be: an ever-living fire, with measures of it kindling, and measures going out." Heraclitus regarded the soul as being a mixture of fire and water, with fire being the more noble part and water the ignoble aspect. He believed the goal of the soul is to be rid of water and become pure fire: the dry soul is the best and it is worldly pleasures that make the soul "moist". He was known as the "weeping philosopher" and died of hydropsy, a swelling due to abnormal accumulation of fluid beneath the skin.

However, Empedocles of Akragas (c. 495 – c. 435 BCE), is best known for having selected all elements as his archai and by the time of Plato (427–347 BCE), the four Empedoclian elements were well established. In the Timaeus, Plato's major cosmological dialogue, the Platonic solid he associated with fire was the tetrahedron which is formed from four triangles and contains the least volume with the greatest surface area. This also makes fire the element with the smallest number of sides, and Plato regarded it as appropriate for the heat of fire, which he felt is sharp and stabbing, (like one of the points of a tetrahedron).

Plato's student Aristotle (384–322 BCE) did not maintain his former teacher's geometric view of the elements, but rather preferred a somewhat more naturalistic explanation for the elements based on their traditional qualities. Fire the hot and dry element, like the other elements, was an abstract principle and not identical with the normal solids, liquids and combustion phenomena we experience: What we commonly call fire. It is not really fire, for fire is an excess of heat and a sort of ebullition; but in reality, of what we call air, the part surrounding the earth is moist and warm, because it contains both vapour and a dry exhalation from the earth. According to Aristotle, the four elements rise or fall toward their natural place in concentric layers surrounding the center of the Earth and form the terrestrial or sublunary spheres.

In ancient Greek medicine, each of the four humours became associated with an element. Yellow bile was the humor identified with fire, since both were hot and dry. Other things associated with fire and yellow bile in ancient and medieval medicine included the season of summer, since it increased the qualities of heat and aridity; the choleric temperament (of a person dominated by the yellow bile humour); the masculine; and the eastern point of the compass.

In alchemy the chemical element of sulfur was often associated with fire and its alchemical symbol and its symbol was an upward-pointing triangle. In alchemic tradition, metals are incubated by fire in the womb of the Earth and alchemists only accelerate their development.

Indian tradition
Agni is a Hindu and Vedic deity. The word agni is Sanskrit for fire (noun), cognate with Latin ignis (the root of English ignite), Russian огонь (fire), pronounced agon. Agni has three forms: fire, lightning and the sun.

Agni is one of the most important of the Vedic gods. He is the god of fire and the accepter of sacrifices. The sacrifices made to Agni go to the deities because Agni is a messenger from and to the other gods. He is ever-young, because the fire is re-lit every day, yet he is also immortal. In Indian tradition fire is also linked to Surya or the Sun and Mangala or Mars, and with the south-east direction.

Teukāya ekendriya is a name used in Jain tradition which refers to Jīvas said to be reincarnated as fire.

Ceremonial magic
Fire and the other Greek classical elements were incorporated into the Golden Dawn system. Philosophus (4=7) is the elemental grade attributed to fire; this grade is also attributed to the Qabalistic Sephirah Netzach and the planet Venus. The elemental weapon of fire is the Wand. Each of the elements has several associated spiritual beings. The archangel of fire is Michael, the angel is Aral, the ruler is Seraph, the king is Djin, and the fire elementals (following Paracelsus) are called salamanders. Fire is considered to be active; it is represented by the symbol for Leo and it is referred to the lower right point of the pentacle in the Supreme Invoking Ritual of the Pentacle. Many of these associations have since spread throughout the occult community.

Tarot
Fire in tarot symbolizes conversion or passion. Many references to fire in tarot are related to the usage of fire in the practice of alchemy, in which the application of fire is a prime method of conversion, and everything that touches fire is changed, often beyond recognition. The symbol of fire was a cue pointing towards transformation, the chemical variant being the symbol delta, which is also the classical symbol for fire. Conversion symbolized can be good, for example, refining raw crudities to gold, as seen in The Devil. Conversion can also be bad, as in The Tower, symbolizing a downfall due to anger. Fire is associated with the suit of rods/wands, and as such, represents passion from inspiration. As an element, fire has mixed symbolism because it represents energy, which can be helpful when controlled, but volatile if left unchecked.

Modern witchcraft
Fire is one of the five elements that appear in most Wiccan traditions influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn.

Freemasonry
In freemasonry, fire is present, for example, during the ceremony of winter solstice, a symbol also of renaissance and energy. Freemasonry takes the ancient symbolic meaning of fire and recognizes its double nature: creation, light, on the one hand, and destruction and purification, on the other.

title: Fire (classical element)


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Air (classical element)

Air or Wind is one of the four classical elements along with water, earth and fire in ancient Greek philosophy and in Western alchemy.

Greek and Roman tradition
According to Plato, it is associated with the octahedron; air is considered to be both hot and wet. The ancient Greeks used two words for air: aer meant the dim lower atmosphere, and aether meant the bright upper atmosphere above the clouds. Plato, for instance writes that "So it is with air: there is the brightest variety which we call aether, the muddiest which we call mist and darkness, and other kinds for which we have no name...." Among the early Greek Pre-Socratic philosophers, Anaximenes (mid-6th century BCE) named air as the arche. A similar belief was attributed by some ancient sources to Diogenes Apolloniates (late 5th century BCE), who also linked air with intelligence and soul (psyche), but other sources claim that his arche was a substance between air and fire. Aristophanes parodied such teachings in his play The Clouds by putting a prayer to air in the mouth of Socrates.

Air was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495-c. 435 BCE) selected four archai for his four roots: air, fire, water, and earth. Ancient and modern opinions differ as to whether he identified air by the divine name Hera, Aidoneus or even Zeus. Empedocles’ roots became the four classical elements of Greek philosophy. Plato (427–347 BCE) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with air is the octahedron which is formed from eight equilateral triangles. This places air between fire and water which Plato regarded as appropriate because it is intermediate in its mobility, sharpness, and ability to penetrate. He also said of air that its minuscule components are so smooth that one can barely feel them.

Plato's student Aristotle (384–322 BCE) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the universe to form the sublunary sphere. According to Aristotle, air is both hot and wet and occupies a place between fire and water among the elemental spheres. Aristotle definitively separated air from aether. For him, aether was an unchanging, almost divine substance that was found only in the heavens, where it formed celestial spheres.

Humorism and temperaments
In ancient Greek medicine, each of the four humours became associated with an element. Blood was the humor identified with air, since both were hot and wet. Other things associated with air and blood in ancient and medieval medicine included the season of spring, since it increased the qualities of heat and moisture; the sanguine temperament (of a person dominated by the blood humour); hermaphrodite (combining the masculine quality of heat with the feminine quality of moisture); and the northern point of the compass.

Alchemy
The alchemical symbol for air is an upward-pointing triangle, bisected by a horizontal line.

Modern reception
The Hermetic Order of the Golden Dawn, founded in 1888, incorporates air and the other Greek classical elements into its teachings. The elemental weapon of air is the dagger which must be painted yellow with magical names and sigils written upon it in violet. Each of the elements has several associated spiritual beings. The archangel of air is Raphael, the angel is Chassan, the ruler is Ariel, the king is Paralda, and the air elementals (following Paracelsus) are called sylphs. Air is considerable and it is referred to the upper left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.

In the Golden Dawn and many other magical systems, each element is associated with one of the cardinal points and is placed under the care of guardian Watchtowers. The Watchtowers derive from the Enochian system of magic founded by Dee. In the Golden Dawn, they are represented by the Enochian elemental tablets. Air is associated with the east, which is guarded by the First Watchtower. Air is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism.

Parallels in non-Western traditions
Air is not one of the traditional five Chinese classical elements. Nevertheless, the ancient Chinese concept of Qi or chi is believed to be close to that of air. Qi is believed to be part of every living thing that exists, as a kind of "life force" or "spiritual energy". It is frequently translated as "energy flow", or literally as "air" or "breath". (For example, tiānqì, literally "sky breath", is the Chinese word for "weather"). The concept of qi is often reified, however no scientific evidence supports its existence.

The element air also appears as a concept in the Buddhist philosophy which has an ancient history in China.

Some Western modern occultists equate the Chinese classical element of metal with air, others with wood due to the elemental association of wind and wood in the bagua.

Enlil was the god of air in ancient Sumer. Shu was the ancient Egyptian deity of air and the husband of Tefnut, goddess of moisture. He became an emblem of strength by virtue of his role in separating Nut from Geb. Shu played a primary role in the Coffin Texts, which were spells intended to help the deceased reach the realm of the afterlife safely. On the way to the sky, the spirit had to travel through the air as one spell indicates: "I have gone up in Shu, I have climbed on the sunbeams."

According to Jain beliefs, the element air is inhabited by one-sensed beings or spirits called vāyukāya ekendriya, sometimes said to inhabit various kinds of winds such as whirlwinds, cyclones, monsoons, west winds and trade winds. Prior to reincarnating into another lifeform, spirits can remain as vāyukāya ekendriya from anywhere between one instant to up to three-thousand years, depending on the karma of the spirits.

title: Air (classical element)


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Water (classical element)

Water is one of the classical elements in ancient Greek philosophy along with air, earth and fire, in the Asian Indian system Panchamahabhuta, and in the Chinese cosmological and physiological system Wu Xing. In contemporary esoteric traditions, it is commonly associated with the qualities of emotion and intuition.

Greek and Roman tradition
Water was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495 – c. 435 BC) selected four archai for his four roots: air, fire, water and earth. Empedocles roots became the four classical elements of Greek philosophy. Plato (427–347 BC) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with water is the icosahedron which is formed from twenty equilateral triangles. This makes water the element with the greatest number of sides, which Plato regarded as appropriate because water flows out of one's hand when picked up, as if it is made of tiny little balls.

Plato's student Aristotle (384–322 BC) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the Universe to form the sublunary sphere. According to Aristotle, water is both cold and wet and occupies a place between air and earth among the elemental spheres.

In ancient Greek medicine, each of the four humours became associated with an element. Phlegm was the humor identified with water, since both were cold and wet. Other things associated with water and phlegm in ancient and medieval medicine included the season of Winter, since it increased the qualities of cold and moisture, the phlegmatic temperament, the feminine and the western point of the compass.

In alchemy, the chemical element of mercury was often associated with water and its alchemical symbol was a downward-pointing triangle.

Indian tradition
Ap (') is the Vedic Sanskrit term for water, in Classical Sanskrit occurring only in the plural is not an element.v, ' (sometimes re-analysed as a thematic singular, '), whence Hindi '. The term is from PIE hxap water.

In Hindu philosophy, the term refers to water as an element, one of the Panchamahabhuta, or "five great elements". In Hinduism, it is also the name of the deva, a personification of water, (one of the Vasus in most later Puranic lists). The element water is also associated with Chandra or the moon and Shukra, who represent feelings, intuition and imagination.

According to Jain tradition, water itself is inhabited by spiritual Jīvas called apakāya ekendriya.

Ceremonial magic
Water and the other Greek classical elements were incorporated into the Golden Dawn system. The elemental weapon of water is the cup. Each of the elements has several associated spiritual beings. The archangel of water is Gabriel, the angel is Taliahad, the ruler is Tharsis, the king is Nichsa and the water elementals are called Ondines. It is referred to the upper right point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.

Modern witchcraft
Water is one of the five elements that appear in most Wiccan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn.

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Earth (classical element)

Earth is one of the classical elements, in some systems being one of the four along with air, fire, and water.

European tradition
Earth is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with qualities of heaviness, matter and the terrestrial world. Due to the hero cults, and chthonic underworld deities, the element of earth is also associated with the sensual aspects of both life and death in later occultism.

Empedocles of Acragas (c. 495 – c. 435 BCE) proposed four archai by which to understand the cosmos: fire, air, water, and earth. Plato (427–347 BCE) believed the elements were geometric forms (the platonic solids) and he assigned the cube to the element of earth in his dialogue Timaeus. Aristotle (384–322 BCE) believed earth was the heaviest element, and his theory of natural place suggested that any earth–laden substances, would fall quickly, straight down, towards the center of the cosmos.

In Classical Greek and Roman myth, various goddesses represented the Earth, seasons, crops and fertility, including Demeter and Persephone; Ceres; the Horae (goddesses of the seasons), and Proserpina; and Hades (Pluto) who ruled the souls of dead in the Underworld.

In ancient Greek medicine, each of the four humours became associated with an element. Black bile was the humor identified with earth, since both were cold and dry. Other things associated with earth and black bile in ancient and medieval medicine included the season of fall, since it increased the qualities of cold and aridity; the melancholic temperament (of a person dominated by the black bile humour); the feminine; and the southern point of the compass.

In alchemy, earth was believed to be primarily dry, and secondarily cold, (as per Aristotle). Beyond those classical attributes, the chemical substance salt, was associated with earth and its alchemical symbol was a downward-pointing triangle, bisected by a horizontal line.

Indian tradition
Prithvi (Sanskrit: ', also ') is the Hindu earth and mother goddess. According to one such tradition, she is the personification of the Earth itself; according to another, its actual mother, being Prithvi Tattwa, the essence of the element earth.

As Prithvi Mata, or "Mother Earth", she contrasts with Dyaus Pita, "father sky". In the Rigveda, earth and sky are frequently addressed as a duality, often indicated by the idea of two complementary "half-shells." In addition, the element Earth is associated with Budha or Mercury who represents communication, business, mathematics and other practical matters.

Jainism mentions one-sensed beings or spirits believed to inhabit the element earth sometimes classified as pṛthvīkāya ekendriya.

Ceremonial magic
Earth and the other Greek classical elements were incorporated into the Golden Dawn system. Zelator is the elemental grade attributed to earth; this grade is also attributed to the Sephirot of Malkuth. The elemental weapon of earth is the Pentacle. Each of the elements has several associated spiritual beings. The archangel of earth is Uriel, the angel is Phorlakh, the ruler is Kerub, the king is Ghob, and the earth elementals (following Paracelsus) are called gnomes. Earth is considered to be passive; it is represented by the symbol for Taurus, and it is referred to the lower left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.

It is sometimes represented by its Tattva or by a downward pointing triangle with a horizontal line through it.

Modern witchcraft
Earth is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism which was in turn inspired by the Golden Dawn.

Other traditions
Earth is represented in the Aztec religion by a house; to the Hindus, a lotus; to the Scythians, a plough; to the Greeks, a wheel; and in Christian iconography; bulls and birds.

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Talk:Classical element

Origins of the 4 elements concept
It seams that the earliest philosophers were trying to understand which of the four elements is the arche, but all of them were aware of the 4 elements concept. So the question is where this concept come from? Who was the first to talk about? Maybe babilonians, or Egyptians or hindus? Did anyone research that ? I did but couldn't find the origins 196.129.68.203 (talk) 07:51, 2 March 2023 (UTC)

Popular culture
Is there a Classical elements in popular culture article or section somewhere? It is a very prevalent theme. Just to list a few, we have Avatar: The Last Airbender, Xiaolin Showdown and Monica's Gang in an Adventure in Time. There's also many works based on the classical four that include a fifth element, such as Captain Planet and The Fifth Element. The concept surely should have a section or article. Mateussf (talk) 10:30, 9 February 2024 (UTC)
 * Update. There was, and it was deleted after this: Articles_for_deletion/Classical_elements_in_popular_culture_(3rd_nomination). Votes say it could be recreated, if properly sourced and relevant. Mateussf (talk) 01:49, 11 February 2024 (UTC)

Restored subsection "Water, air, or fire?"
I have restored the small subsection "Water, air, or fire?". Someone else originally added the content; I only did some rephrasing, reordering, and added the subheading. I'm sure this could have been done much better by a more capable editor. I haven't checked the sources and don't know to what extent the information is correct and relevant. It seems somewhat interesting and relevant to me. The subsection has recently been removed and there may or may not be good reasons for that. It would be nice with an explanation for its deletion though. The Cosmic Ocean (Please feel free to modify or undo any of my edits as deemed appropriate.) 15:36, 13 March 2024 (UTC)

Jainism
Content was recently removed by William M. Connolley by saying it is more about souls than elements. While I suppose it focuses more on souls believed to inhabit elements than the elements themselves, I still felt like it would be worth keeping because it shows the religious significance that the concept of the elements have in Jainism.

One of the sources added that can be read here even mentions a connection to the elements earth, air, fire and water, by stating "Plants, various one-celled animals, and ‘elemental’ beings (beings made of one of the four elements—earth, air, fire, or water) have only one sense."

However, for the other source that was added, I made a link to the journal itself instead of linking the pages of the journal because more than one page contains information that was added to the article, so I was not able to link every different page. But if you want to see the specific part where elements are mentioned, see this link of page 353 which states "Ekendriya jivas inhabit the elements above enumerated" (in this case it is referring to what the Ekendriya are said to inhabit in pages 351 and 352 which are the elements earth, water, fire and air). Opskind (talk) 15:51, 15 June 2024 (UTC)

title: Talk:Classical element


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Blue Jam

Blue Jam was an ambient, surreal dark comedy and horror radio programme created and directed by Chris Morris. It was broadcast on BBC Radio 1 in the early hours of the morning, for three series from 1997 to 1999.

The programme gained cult status due to its unique mix of surreal monologue, ambient soundtrack, synthesised voices, heavily edited broadcasts and recurring sketches. It featured vocal performances of Kevin Eldon, Julia Davis, Mark Heap, David Cann and Amelia Bullmore, with Morris himself delivering disturbing monologues, one of which was revamped and made into the BAFTA-winning short film My Wrongs #8245–8249 & 117. Writers who contributed to the programme included Graham Linehan, Arthur Mathews, Peter Baynham, David Quantick, Jane Bussmann, Robert Katz and the cast.

The programme was adapted into the TV series Jam, which aired in 2000. All episodes of Blue Jam are currently available for streaming and download on the Internet Archive and Youtube.

Production
On his inspiration for making the show, Morris commented: "It was so singular, and it came from a mood, quite a desolate mood. I had this misty, autumnal, boggy mood anyway, so I just went with that. But no doubt getting to the end of something like Brass Eye, where you've been forced to be a sort of surrogate lawyer, well, that's the most creatively stifling thing you could possibly do." Morris also described the show as being "like the nightmares you have when you fall asleep listening to the BBC World Service" (a reference to the World Service also appears in one of the monologues read by Morris).

Morris originally requested that the show be broadcast at 3 a.m. on Radio 1 "because at that hour, on insomniac radio, the amplitude of terrible things is enormously overblown". As a compromise, the show was broadcast at midnight without much promotion. Morris reportedly included sketches too graphic or transgressive for radio that he knew would be cut so as to make his other material seem less transgressive in comparison. During the airing of episode 6 of series one, a re-editing of the Archbishop of Canterbury's speech at Princess Diana's funeral was deemed too offensive for broadcast, and was switched with a different episode as it aired.

Format and style
Each episode opened (and closed) with a short spoken monologue (delivered by Morris) describing, in surreal, broken language, various bizarre feelings and situations (for example: "when you sick so sad you cry, and in crying cry a whole leopard from your eye"), set to ambient music interspersed with short clips of other songs and sounds. The introduction would always end with "welcome in Blue Jam", inviting the listener, who is presumably experiencing such feelings, to get lost in the program. (This format was replicated in the television adaptation Jam, often reusing opening monologues from series 3 of the radio series.) The sketches within dealt with heavy and taboo topics, such as murder, suicide, missing or dead children, and rape.

Common recurring sketches

 * Doctor (played by David Cann): "The Doctor" is a seemingly "normal" physician working in a standard British medical practice. However, he has a habit of treating his patients in bizarre and often disturbing ways, such as prescribing heroin for a cold, kissing patients on various body parts to make swellings go away, making a man with a headache jump up and down to make his penis swing (while mirroring the patient's bewildered jumping himself) and making a patient leave and go into the next room so he can examine him over the telephone. His name is revealed to be Michael Perlin in several sketches.
 * The Monologue Man (played by Chris Morris): Short stories, often up to 10 minutes in length, written from the perspective of a lonely and socially inept man. Each story usually involves the protagonist's acquaintance Suzy in some capacity.
 * Michael Alexander St. John: A parody of hyperbolic and pun-laden radio presenting, St. John presents items such as the top 10 singles charts and the weekend's gigs in an incongruous upper class English accent
 * Bad Sex: Short clips of two lovers (played by Julia Davis and Kevin Eldon) making increasingly bizarre erotic requests of one another, such as to "shit your leg off" and "make your spunk come out green".
 * The Interviewer (played by Chris Morris): conducting real interviews with celebrities such as Andrew Morton and Jerry Springer, Morris confuses and mocks his subjects with ambiguous and odd questions.
 * Mr. Ventham (played by Mark Heap): An extremely awkward man who requires one-to-one consultations with Mr. Reilly (played by David Cann), who seems to be his psychologist, for the most banal of matters.

The sketches not listed are often in the style of a documentary; characters speak as if being interviewed about a recent event. In one sketch, a character voiced by Morris describes a man attempting to commit suicide by jumping off a second-story balcony repeatedly; in another, an angry man (Eldon) shouts about how his car, after being picked up from the garage, is only four feet long.

Radio stings
Morris included a series of 'radio stings', bizarre sequences of sounds and prose as a parody of modern DJs' own soundbites and self-advertising pieces. Each one revolves around a contemporary DJ, such as Chris Moyles, Jo Whiley and Mark Goodier, typically involving each DJ dying in a graphic way or going mad in some form – for example, Chris Moyles covering himself in jam and hanging himself from the top of a building.

Episodes
Three series were produced, with a total of eighteen episodes. All episodes were originally broadcast weekly on BBC Radio 1. Series 1 was broadcast from 14 November to 19 December 1997; series 2 was broadcast from 27 March to 1 May 1998; and series 3 broadcast from 21 January to 25 February 1999.

 * Series 1 – (Fridays) 14 November 1997 to 19 December 1997, from 00:00 to 01:00.
 * Series 2 – (Fridays) 27 March 1998 to 1 May 1998, from 01:00 to 02:00.
 * Series 3 – (Thursdays) 21 January 1999 to 25 February 1999, from 00:00 to 01:00.

The first five episodes of series 1 of Blue Jam were repeated by BBC Radio 4 Extra in February and March 2014, and series 2 was rebroadcast in December.

Music
Blue Jam features songs, generally of a downtempo nature, interspersed between (and sometimes during) sketches. Artists featured includes Massive Attack, Air, Morcheeba, The Chemical Brothers, Björk, Aphex Twin, Everything But the Girl and Dimitri from Paris, as well as various non-electronic artists including Sly and the Family Stone, Serge Gainsbourg, The Cardigans and Eels.

Reception
Blue Jam was favourably reviewed on several occasions by The Guardian   and also received a positive review by The Independent.

Digital Spy wrote in 2014: "It's a heady cocktail that provokes an odd, unsettling reaction in the listener, yet Blue Jam is still thumpingly and frequently laugh-out-loud hilarious." Hot Press called it "as odd as comedy gets".

CD release
A CD of a number of Blue Jam sketches was released on 23 October 2000 by record label Warp. Although the CD claims to have 22 tracks, the last one, "www.bishopslips.com", is not a track, but rather a reference to the "Bishopslips" sketch, which was cut in the middle of a broadcast. Most of the sketches on the CD were remade for Jam.

 * Track listing

 * 1) "Blue Jam Intro"
 * 2) "Doc Phone"
 * 3) "Lamacq sting"
 * 4) "4 ft Car"
 * 5) "Suicide Journalist"
 * 6) "Acupuncture"
 * 7) "Bad Sex"
 * 8) "Mayo Sting"
 * 9) "Unflustered Parents"
 * 10) "Moyles Sting"
 * 11) "TV Lizards"
 * 12) "Doc Cock"
 * 13) "Hobbs Sting"
 * 14) "Morton Interview"
 * 15) "Fix It Girl"
 * 16) "Porn"
 * 17) "Kids Party"
 * 18) "Club News"
 * 19) "Whiley Sting"
 * 20) "Little Girl Balls"
 * 21) "Blue Jam Outro"
 * 22) "www.bishopslips.com" (not a real track)

Related shows
Blue Jam was later made for television and broadcast on Channel 4 as Jam. It used unusual editing techniques to achieve an unnerving ambience in keeping with the radio show. Many of the sketches were lifted from the radio version, even to the extent of simply setting images to the radio soundtrack. A subsequent "re-mixed" airing, called Jaaaaam was even more extreme in its use of post-production gadgetry, often heavily distorting the footage.

Blue Jam shares parallels with early editions of a US public radio show Joe Frank: Work in Progress from the mid-1980s, that Joe Frank did on the NPR affiliate station, KCRW, in Santa Monica, California.

title: Blue Jam