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French Republican calendar

The French Republican calendar (calendrier républicain français), also commonly called the French Revolutionary calendar (calendrier révolutionnaire français), was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871, and meant to replace the Gregorian calendar.

The calendar consisted of twelve 30-day months, each divided into three 10-day cycles similar to weeks, plus five or six intercalary days at the end to fill out the balance of a solar year. It was designed in part to remove all religious and royalist influences from the calendar, and it was part of a larger attempt at decimalisation in France (which also included decimal time of day, decimalisation of currency, and metrication). It was used in government records in France and other areas under French rule, including Belgium, Luxembourg, and parts of the Netherlands, Germany, Switzerland, Malta, and Italy.

Beginning and ending
The National Constituent Assembly at first intended to create a new calendar marking the "era of Liberty", beginning on 14 July 1789, the date of the Storming of the Bastille. However, on 2 January 1792 its successor the Legislative Assembly decided that Year IV of Liberty had begun the day before. Year I had therefore begun on 1 January 1789.

On 21 September 1792, the French First Republic was proclaimed, and the new National Convention decided that 1792 was to be known as Year I of the French Republic. It decreed on 2 January 1793 that Year II of the Republic had begun the day before. However, the new calendar as adopted by the Convention in October 1793 made 22 September 1792 the first day of Year I.

Ultimately, the calendar came to commemorate the Republic, and not the Revolution. The Common Era, commemorating the birth of Jesus Christ, was abolished and replaced with l'ère républicaine, the Republican Era, signifying the "age of reason" overcoming superstition, as part of the campaign of dechristianization.

The First Republic ended with the coronation of Napoleon I as Emperor on 11 Frimaire, Year XIII, or 2 December 1804. Despite this, the republican calendar continued to be used until 1 January 1806, when Napoleon declared it abolished. It was briefly used again for a few weeks of the Paris Commune, in May 1871.

Precursor
The prominent atheist essayist and philosopher Sylvain Maréchal published the first edition of his Almanach des Honnêtes-gens (Almanac of Honest People) in 1788. The first month in the almanac is "Mars, ou Princeps" (March, or First), the last month is "Février, ou Duodécembre" (February, or Twelfth). The lengths of the months are the same as those in the Gregorian calendar; however, the 10th, 20th, and 30th days are singled out of each month as the end of a décade (group of ten days). Individual days were assigned, instead of to the traditional saints, to people noteworthy for mostly secular achievements. Later editions of the almanac would switch to the Republican Calendar.

History
The days of the French Revolution and Republic saw many efforts to sweep away various trappings of the Ancien Régime (the old feudal monarchy); some of these were more successful than others. The new Republican government sought to institute, among other reforms, a new social and legal system, a new system of weights and measures (which became the metric system), and a new calendar. Amid nostalgia for the ancient Roman Republic, the theories of the Age of Enlightenment were at their peak, and the devisers of the new systems looked to nature for their inspiration. Natural constants, multiples of ten, and Latin as well as Ancient Greek derivations formed the fundamental blocks from which the new systems were built.

The new calendar was created by a commission under the direction of the politician Gilbert Romme seconded by and Charles-François Dupuis. They associated with their work the chemist Louis-Bernard Guyton de Morveau, the mathematician and astronomer Joseph-Louis Lagrange, the astronomer Jérôme Lalande, the mathematician Gaspard Monge, the astronomer and naval geographer Alexandre Guy Pingré, and the poet, actor and playwright Fabre d'Églantine, who invented the names of the months, with the help of André Thouin, gardener at the Jardin des plantes of the Muséum National d'Histoire Naturelle in Paris. As the rapporteur of the commission, Charles-Gilbert Romme presented the new calendar to the Jacobin-controlled National Convention on 23 September 1793, which adopted it on 24 October 1793 and also extended it proleptically to its epoch of 22 September 1792. It is because of his position as rapporteur of the commission that the creation of the republican calendar is attributed to Romme.

The calendar is frequently named the "French Revolutionary Calendar" because it was created during the Revolution, but this is a slight misnomer. In France, it is known as the calendrier républicain as well as the calendrier révolutionnaire. There was initially a debate as to whether the calendar should celebrate the Great Revolution, which began in July 1789, or the Republic, which was established in 1792. Immediately following 14 July 1789, papers and pamphlets started calling 1789 year I of Liberty and the following years II and III. It was in 1792, with the practical problem of dating financial transactions, that the legislative assembly was confronted with the problem of the calendar. Originally, the choice of epoch was either 1 January 1789 or 14 July 1789. After some hesitation the assembly decided on 2 January 1792 that all official documents would use the "era of Liberty" and that the year IV of Liberty started on 1 January 1792. This usage was modified on 22 September 1792 when the Republic was proclaimed and the Convention decided that all public documents would be dated Year I of the French Republic. The decree of 2 January 1793 stipulated that the year II of the Republic began on 1 January 1793; this was revoked with the introduction of the new calendar, which set 22 September 1793 as the beginning of year II. The establishment of the Republic was used as the epochal date for the calendar; therefore, the calendar commemorates the Republic, and not the Revolution.

French coins of the period naturally used this calendar. Many show the year (an) in Arabic numbers, although Roman numerals were used on some issues. Year 11 coins typically have a XI date to avoid confusion with the Roman II.

The French Revolution is usually considered to have ended with the coup of 18 Brumaire, Year VIII (9 November 1799), the coup d'état of Napoleon Bonaparte against the established constitutional regime of the Directoire.

The Concordat of 1801 re-established the Roman Catholic Church as an official institution in France, although not as the state religion of France. The concordat took effect from Easter Sunday, 28 Germinal, Year XI (8 April 1802); it restored the names of the days of the week to the ones from the Gregorian calendar, and fixed Sunday as the official day of rest and religious celebration. However, the other attributes of the republican calendar, the months, and years, remained as they were.

The French Republic ended with the coronation of Napoleon as Empereur des Français (Emperor of the French) on 11 Frimaire, Year XIII (2 December 1804), but the republican calendar would remain in place for another year. Napoleon finally abolished the republican calendar with effect from 1 January 1806 (the day after 10 Nivôse Year XIV), a little over twelve years after its introduction. It was, however, used again briefly in the Journal officiel for some dates during a short period of the Paris Commune, 6–23 May 1871 (16 Floréal–3 Prairial Year LXXIX).

Calendar design
Years appear in writing as Roman numerals (usually), with epoch 22 September 1792, the beginning of the "Republican Era" (the day the French First Republic was proclaimed, one day after the Convention abolished the monarchy). As a result, Roman Numeral I indicates the first year of the republic, that is, the year before the calendar actually came into use. By law, the beginning of each year was set at midnight, beginning on the day the apparent autumnal equinox falls at the Paris Observatory.

There were twelve months, each divided into three ten-day weeks called décades. The tenth day, décadi, replaced Sunday as the day of rest and festivity. The five or six extra days needed to approximate the solar or tropical year were placed after the final month of each year and called complementary days. This arrangement was an almost exact copy of the calendar used by the Ancient Egyptians, though in their case the year did not begin and end on the autumnal equinox.

A period of four years ending on a leap day was to be called a "Franciade". The name "Olympique" was originally proposed but changed to Franciade to commemorate the fact that it had taken the revolution four years to establish a republican government in France.

The leap year was called Sextile, an allusion to the "bissextile" leap years of the Julian and Gregorian calendars, because it contained a sixth complementary day.

Decimal time
Each day in the Republican Calendar was divided into ten hours, each hour into 100 decimal minutes, and each decimal minute into 100 decimal seconds. Thus an hour was 144 conventional minutes (2.4 times as long as a conventional hour), a minute was 86.4 conventional seconds (44% longer than a conventional minute), and a second was 0.864 conventional seconds (13.6% shorter than a conventional second).

Clocks were manufactured to display this decimal time, but it did not catch on. Mandatory use of decimal time was officially suspended 7 April 1795, although some cities continued to use decimal time as late as 1801.

The numbering of years in the Republican Calendar by Roman numerals ran counter to this general decimalization tendency.

Months
The Republican calendar year began the day the autumnal equinox occurred in Paris, and had twelve months of 30 days each, which were given new names based on nature, principally having to do with the prevailing weather in and around Paris and sometimes evoking the Medieval Labours of the Months. The extra five or six days in the year were not given a month designation, but considered Sansculottides or Complementary Days.
 * Autumn:
 * Vendémiaire (from French vendange, which means grape harvest, derived from Latin vindemia 'vintage'), starting 22, 23, or 24 September
 * Brumaire (from French brume 'mist', from Latin brūma 'winter solstice; winter; winter cold'), starting 22, 23, or 24 October
 * Frimaire (from French frimas 'frost'), starting 21, 22, or 23 November
 * Winter:
 * Nivôse (from Latin nivosus 'snowy'), starting 21, 22, or 23 December
 * Pluviôse (from French pluvieux, derived from Latin pluvius 'rainy'), starting 20, 21, or 22 January
 * Ventôse (from French venteux, derived from Latin ventosus 'windy'), starting 19, 20, or 21 February
 * Spring:
 * Germinal (from French germination), starting 21 or 22 March
 * Floréal (from French fleur, derived from Latin flos 'flower'), starting 20 or 21 April
 * Prairial (from French prairie 'meadow'), starting 20 or 21 May
 * Summer:
 * Messidor (from Latin messis 'harvest'), starting 19 or 20 June
 * Thermidor (from Greek thermon 'summer heat'), starting 19 or 20 July; on many printed calendars of Year II (1793–94), the month of Thermidor was named Fervidor (from Latin fervidus, "burning hot")
 * Fructidor (from Latin fructus 'fruit'), starting 18 or 19 August

Most of the month names were new words coined from French, Latin, or Greek. The endings of the names are grouped by season. Dor means 'giving' in Greek.

In Britain, a contemporary wit mocked the Republican Calendar by calling the months: Wheezy, Sneezy, and Freezy; Slippy, Drippy, and Nippy; Showery, Flowery, and Bowery; Hoppy, Croppy, and Poppy. The historian Thomas Carlyle suggested somewhat more serious English names in his 1837 work The French Revolution: A History, namely Vintagearious, Fogarious, Frostarious, Snowous, Rainous, Windous, Buddal, Floweral, Meadowal, Reapidor, Heatidor, and Fruitidor. Like the French originals, they are neologisms suggesting a meaning related to the season.

Ten days of the week
The month is divided into three décades or "weeks" of ten days each, named simply:
 * primidi (first day)
 * duodi (second day)
 * tridi (third day)
 * quartidi (fourth day)
 * quintidi (fifth day)
 * sextidi (sixth day)
 * septidi (seventh day)
 * octidi (eighth day)
 * nonidi (ninth day)
 * décadi (tenth day)

Décadis became official days of rest instead of Sundays, in order to diminish the influence of the Roman Catholic Church. They were used for the festivals of a succession of new religions meant to replace Catholicism: the Cult of Reason, the Cult of the Supreme Being, the Decadary Cult, and Theophilanthropy. Christian holidays were officially abolished in favor of revolutionary holidays.

The law of 13 Fructidor year VI (August 30, 1798) required that marriages must only be celebrated on décadis. This law was applied from the 1st Vendémiaire year VII (September 22, 1798) to 28 Pluviôse year VIII (February 17, 1800).

Décades were abandoned at the changeover from Germinal to Floréal an X (20 to 21 April 1802), after Napoleon's Concordat with the Pope.

Rural calendar
The Roman Catholic Church used a calendar of saints, which named each day of the year after an associated saint. To reduce the influence of the Church, Fabre d'Églantine introduced a Rural Calendar in which each day of the year had a unique name associated with the rural economy, stated to correspond to the time of year. Every décadi (ending in 0) was named after an agricultural tool. Each quintidi (ending in 5) was named for a common animal. The rest of the days were named for "grain, pasture, trees, roots, flowers, fruits" and other plants, except for the first month of winter, Nivôse, during which the rest of the days were named after minerals.

"Our starting point was the idea of celebrating, through the calendar, the agricultural system, and of leading the nation back to it, marking the times and the fractions of the year by intelligible or visible signs taken from agriculture and the rural economy. (...)

As the calendar is something that we use so often, we must take advantage of this frequency of use to put elementary notions of agriculture before the people – to show the richness of nature, to make them love the fields, and to methodically show them the order of the influences of the heavens and of the products of the earth.

The priests assigned the commemoration of a so-called saint to each day of the year: this catalogue exhibited neither utility nor method; it was a collection of lies, of deceit or of charlatanism.

We thought that the nation, after having kicked out this canonised mob from its calendar, must replace it with the objects that make up the true riches of the nation, worthy objects not from a cult, but from agriculture – useful products of the soil, the tools that we use to cultivate it, and the domesticated animals, our faithful servants in these works; animals much more precious, without doubt, to the eye of reason, than the beatified skeletons pulled from the catacombs of Rome.

So we have arranged in the column of each month, the names of the real treasures of the rural economy. The grains, the pastures, the trees, the roots, the flowers, the fruits, the plants are arranged in the calendar, in such a way that the place and the day of the month that each product occupies is precisely the season and the day that Nature presents it to us."

The following pictures, showing twelve allegories for the months, were illustrated by French painter Louis Lafitte (1779–1828), and engraved by Salvatore Tresca (1750–1815).

Complementary days
Five extra days – six in leap years – were national holidays at the end of every year. These were originally known as les sans-culottides (after sans-culottes), but after year III (1795) as les jours complémentaires:
 * 1st complementary day: La Fête de la Vertu, "Celebration of Virtue", on 17 or 18 September
 * 2nd complementary day: La Fête du Génie, "Celebration of Talent", on 18 or 19 September
 * 3rd complementary day: La Fête du Travail, "Celebration of Labour", on 19 or 20 September
 * 4th complementary day: La Fête de l'Opinion, "Celebration of Convictions", on 20 or 21 September
 * 5th complementary day: La Fête des Récompenses, "Celebration of Honors (Awards)", on 21 or 22 September
 * 6th complementary day: La Fête de la Révolution, "Celebration of the Revolution", on 22 or 23 September (on leap years only)

During the Republic

Below are the Gregorian dates each year of the Republican Era (Ère Républicaine in French) began while the calendar was in effect.

 * Extra (sextile) day inserted before date, due to previous leap year

After the Republic
The Republican Calendar was abolished in the year XIV (1805). After this year, there are two historically attested calendars which may be used to determine dates. Both calendars gave the same dates for years 17 to 52 (1808–1844), always beginning on 23 September, and it was suggested, but never adopted, that the reformed calendar be implemented during this period, before the Republican Calendar was abolished.
 *  Republican Calendar: The only legal calendar during the Republic. The first day of the year, 1 Vendémiaire, is always the day the autumn equinox occurs in Paris. About every 30 years, leap years are 5 years apart instead of 4, as happened between the leap years 15 and 20. The lengths of the first 524 years were calculated by Delambre.
 * Reformed Republican Calendar: Following a proposal by Delambre in order to make leap years regular and predictable, with leap years being every year divisible by 4, except years divisible by 100 and not by 400. Years divisible by 4000 would also be ordinary years. Intended to be implemented in year 3, the reformed calendar was abandoned after the death of the head of the calendar committee, Gilbert Romme. This calendar also has the benefit that every year in the third century of the Republican Era (1992–2091) begins on 22 September.

 * Extra (sextile) day inserted before date, due to previous leap year

Current date and time
For this calendar, Delambre's revised method of calculating leap years is used. Other methods may differ by one day. Time may be cached and therefore not accurate. Decimal time is according to Paris mean time, which is 9 minutes 21 seconds (6.49 decimal minutes) ahead of Greenwich Mean Time. (This tool calibrates the time, if calibration is desired.)

Criticism and shortcomings
Leap years in the calendar are a point of great dispute, due to the contradicting statements in the establishing decree stating: "Each year begins at midnight, with the day on which the true autumnal equinox falls for the Paris Observatory." and: "The four-year period, after which the addition of a day is usually necessary, is called the Franciade in memory of the revolution which, after four years of effort, led France to republican government. The fourth year of the Franciade is called Sextile."

These two specifications are incompatible, as leap years defined by the autumnal equinox in Paris do not recur on a regular four-year schedule. It was erroneously believed that one leap day would be skipped automatically every 129 years, on average, but actually five years would sometimes pass between leap years, about three times per century. Thus, the years III, VII, and XI were observed as leap years, and the years XV and XX were also planned as such, even though they were five years apart.

A fixed arithmetic rule for determining leap years was proposed by Jean Baptiste Joseph Delambre and presented to the Committee of Public Education by Gilbert Romme on 19 Floréal An III (8 May 1795). The proposed rule was to determine leap years by applying the rules of the Gregorian calendar to the years of the French Republic (years IV, VIII, XII, etc. were to be leap years) except that year 4000 (the last year of ten 400-year periods) should be a common year instead of a leap year. Shortly thereafter, Romme was sentenced to the guillotine and committed suicide, and the proposal was never adopted, although Jérôme Lalande repeatedly proposed it for a number of years. The proposal was intended to avoid uncertain future leap years caused by the inaccurate astronomical knowledge of the 1790s (even today, this statement is still valid due to the uncertainty in ΔT). In particular, the committee noted that the autumnal equinox of year 144 was predicted to occur at 11:59:40 pm local apparent time in Paris, which was closer to midnight than its inherent 3 to 4 minute uncertainty.

The calendar was abolished by an act dated 22 Fructidor an XIII (9 September 1805) and signed by Napoleon, which referred to a report by Michel-Louis-Étienne Regnaud de Saint-Jean d'Angély and Jean Joseph Mounier, listing two fundamental flaws. The report also noted that the 10-day décade was unpopular and had already been suppressed three years earlier in favor of the seven-day week, removing what was considered by some as one of the calendar's main benefits. The 10-day décade was unpopular with laborers because they received only one full day of rest out of ten, instead of one in seven, although they also got a half-day off on the fifth day (thus 36 full days and 36 half days in a year, for a total of 54 free days, compared to the usual 52 or 53 Sundays). It also, by design, conflicted with Sunday religious observances.
 * 1) The rule for leap years depended upon the uneven course of the sun, rather than fixed intervals, so that one must consult astronomers to determine when each year started, especially when the equinox happened close to midnight, as the exact moment could not be predicted with certainty.
 * 2) Both the era and the beginning of the year were chosen to commemorate a historical event that occurred on the first day of autumn in France, whereas the other European nations began the year near the beginning of winter or spring, thus being impediments to the calendar's adoption in Europe and America, and even a part of the French nation, where the Gregorian calendar continued to be used, as it was required for religious purposes.

Another criticism of the calendar was that despite the poetic names of its months, they were tied to the climate and agriculture of metropolitan France and therefore not applicable to France's overseas territories.

Famous dates and other cultural references
The "Coup of 18 Brumaire" or "Brumaire" was the coup d'état of Napoleon Bonaparte on 18 Brumaire An VIII (9 November 1799), which many historians consider to be the end of the French Revolution. Karl Marx's 1852 essay The Eighteenth Brumaire of Louis Bonaparte compares the coup d'état of 1851 of Louis Napoléon unfavorably to his uncle's earlier coup, with the statement "History repeats ... first as tragedy, then as farce".

Another famous revolutionary date is 9 Thermidor An II (27 July 1794), the date the Convention turned against Maximilien Robespierre, who, along with others associated with the Mountain, was guillotined the following day. Based on this event, the term "Thermidorian" entered the Marxist vocabulary as referring to revolutionaries who destroy the revolution from the inside and turn against its true aims. For example, Leon Trotsky and his followers used this term about Joseph Stalin.

Émile Zola's novel Germinal takes its name from the calendar's month of Germinal.

The seafood dish Lobster Thermidor was named after the 1891 play Thermidor, set during the Revolution.

The French frigates of the Floréal class all bear names of Republican months.

A decree of the National Convention on 9 Brumaire An III, 30 October 1794, established the École normale supérieure. The date appears prominently above the main door of the school.

The French composer Fromental Halévy was born 7 Prairial VIII (27 May 1799), the day of fromental (oatgrass).

Neil Gaiman's The Sandman series included a story called "Thermidor" that takes place in that month during the French Revolution.

title: French Republican calendar


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Freeman Dyson

Freeman John Dyson (15 December 1923 – 28 February 2020) was a British-American theoretical physicist and mathematician known for his works in quantum field theory, astrophysics, random matrices, mathematical formulation of quantum mechanics, condensed matter physics, nuclear physics, and engineering. He was professor emeritus in the Institute for Advanced Study in Princeton and a member of the board of sponsors of the Bulletin of the Atomic Scientists.

Dyson originated several concepts that bear his name, such as Dyson's transform, a fundamental technique in additive number theory, which he developed as part of his proof of Mann's theorem; the Dyson tree, a hypothetical genetically engineered plant capable of growing in a comet; the Dyson series, a perturbative series where each term is represented by Feynman diagrams; the Dyson sphere, a thought experiment that attempts to explain how a space-faring civilization would meet its energy requirements with a hypothetical megastructure that completely encompasses a star and captures a large percentage of its power output; and Dyson's eternal intelligence, a means by which an immortal society of intelligent beings in an open universe could escape the prospect of the heat death of the universe by extending subjective time to infinity while expending only a finite amount of energy.

Dyson disagreed with the scientific consensus on climate change. He believed that some of the effects of increased CO$2$ levels are favourable and not taken into account by climate scientists, such as increased agricultural yield, and further that the positive benefits of CO$2$ likely outweigh the negative effects. He was sceptical about the simulation models used to predict climate change, arguing that political efforts to reduce causes of climate change distract from other global problems that should take priority.

Early life
Dyson was born on 15 December 1923, in Crowthorne in Berkshire, England. He was the son of Mildred and the composer George Dyson, who was later knighted. His mother had a law degree, and after Dyson was born she worked as a social worker. Dyson had one sibling, his older sister, Alice, who remembered him as a boy surrounded by encyclopedias and always calculating on sheets of paper. At the age of four he tried to calculate the number of atoms in the Sun. As a child, he showed an interest in large numbers and in the solar system, and was strongly influenced by the book Men of Mathematics by Eric Temple Bell. Politically, Dyson said he was "brought up as a socialist".

From 1936 to 1941 Dyson was a scholar at Winchester College, where his father was Director of Music. At the age of 17 he studied pure mathematics with Abram Besicovitch as his tutor at Trinity College, Cambridge, where he won a scholarship at age 15. During this stay, Dyson also practised night climbing on the university buildings, and once walked from Cambridge to London in a day with his friend Oscar Hahn, nephew of Kurt Hahn, who was a wheelchair user due to polio.

At the age of 19 he was assigned to war work in the Operational Research Section (ORS) of RAF Bomber Command, where he developed analytical methods for calculating the ideal density for bomber formations to help the Royal Air Force bomb German targets during the Second World War. After the war, Dyson was readmitted to Trinity College, where he obtained a BA degree in mathematics. From 1946 to 1949 he was a fellow of his college, occupying rooms just below those of the philosopher Ludwig Wittgenstein, who resigned his professorship in 1947.

In 1947 Dyson published two papers in number theory. Friends and colleagues described him as shy and self-effacing, with a contrarian streak that his friends found refreshing but intellectual opponents found exasperating. "I have the sense that when consensus is forming like ice hardening on a lake, Dyson will do his best to chip at the ice", Steven Weinberg said of him. His friend the neurologist and author Oliver Sacks said: "A favourite word of Freeman's about doing science and being creative is the word 'subversive'. He feels it's rather important not only to be not orthodox, but to be subversive, and he's done that all his life."

Career in the United States
On G. I. Taylor's advice and recommendation, Dyson moved to the United States in 1947 as a Commonwealth Fellow for postgraduate study with Hans Bethe at Cornell University (1947–1948). There he made the acquaintance of Richard Feynman. Dyson recognized the brilliance of Feynman and worked with him. He then moved to the Institute for Advanced Study (1948–1949), before returning to England (1949–51), where he was a research fellow at the University of Birmingham. In 1949, Dyson demonstrated the equivalence of two formulations of quantum electrodynamics (QED): Richard Feynman's diagrams and the operator method developed by Julian Schwinger and Shin'ichirō Tomonaga. He was the first person after their creator to appreciate the power of Feynman diagrams and his paper written in 1948 and published in 1949 was the first to make use of them. He said in that paper that Feynman diagrams were not just a computational tool but a physical theory and developed rules for the diagrams that completely solved the renormalization problem. Dyson's paper and his lectures presented Feynman's theories of QED in a form that other physicists could understand, facilitating the physics community's acceptance of Feynman's work. J. Robert Oppenheimer, in particular, was persuaded by Dyson that Feynman's new theory was as valid as Schwinger's and Tomonaga's. Also in 1949, in related work, Dyson invented the Dyson series. It was this paper that inspired John Ward to derive his celebrated Ward–Takahashi identity.

Dyson joined the faculty at Cornell as a physics professor in 1951, though he still had no doctorate. In December 1952, Oppenheimer, the director of the Institute for Advanced Study in Princeton, New Jersey, offered Dyson a lifetime appointment at the institute, "for proving me wrong", in Oppenheimer's words. Dyson remained at the Institute until the end of his career. In 1957 he became a US citizen. From 1957 to 1961 Dyson worked on Project Orion, which proposed the possibility of space-flight using nuclear pulse propulsion. A prototype was demonstrated using conventional explosives, but the 1963 Partial Test Ban Treaty, in which Dyson was involved and which he supported, permitted only underground nuclear weapons testing, and the project was abandoned in 1965.

In 1958 Dyson was a member of the design team under Edward Teller for TRIGA, a small, inherently safe nuclear reactor used throughout the world in hospitals and universities for the production of medical isotopes.

In 1966, independently of Elliott H. Lieb and Walter Thirring, Dyson and Andrew Lenard published a paper proving that the Pauli exclusion principle plays the main role in the stability of matter. Hence it is not the electromagnetic repulsion between outer-shell orbital electrons that prevents two stacked wood blocks from coalescing into a single piece, but the exclusion principle applied to electrons and protons that generates the classical macroscopic normal force. In condensed matter physics, Dyson also analysed the phase transition of the Ising model in one dimension and spin waves.

Dyson also did work in a variety of topics in mathematics, such as topology, analysis, number theory and random matrices. In 1973 the number theorist Hugh Lowell Montgomery was visiting the Institute for Advanced Study and had just made his pair correlation conjecture concerning the distribution of the zeros of the Riemann zeta function. He showed his formula to the mathematician Atle Selberg, who said that it looked like something in mathematical physics and that Montgomery should show it to Dyson, which he did. Dyson recognized the formula as the pair correlation function of the Gaussian unitary ensemble, which physicists have studied extensively. This suggested that there might be an unexpected connection between the distribution of primes (2, 3, 5, 7, 11, ...) and the energy levels in the nuclei of heavy elements such as uranium.

Around 1979 Dyson worked with the Institute for Energy Analysis on climate studies. This group, under Alvin Weinberg's direction, pioneered multidisciplinary climate studies, including a strong biology group. Also during the 1970s, Dyson worked on climate studies conducted by the JASON defense advisory group.

Dyson retired from the Institute for Advanced Study in 1994. In 1998 he joined the board of the Solar Electric Light Fund. In 2003 he was president of the Space Studies Institute, the space research organization founded by Gerard K. O'Neill; in 2013 he was on its board of trustees. Dyson was a longtime member of the JASON group.

Dyson won numerous scientific awards, but never a Nobel Prize. Nobel physics laureate Steven Weinberg said that the Nobel committee "fleeced" Dyson, but Dyson remarked in 2009, "I think it's almost true without exception if you want to win a Nobel Prize, you should have a long attention span, get hold of some deep and important problem and stay with it for ten years. That wasn't my style." Dyson was a regular contributor to The New York Review of Books, and published a memoir, Maker of Patterns: An Autobiography Through Letters in 2018.

In 2012 Dyson published (with William H. Press) a fundamental new result about the prisoner's dilemma in the Proceedings of the National Academy of Sciences of the United States of America. He wrote a foreword to a treatise on psychic phenomena in which he concluded that "ESP is real... but cannot be tested with the clumsy tools of science".

Personal life and death
Dyson married his first wife, the Swiss mathematician Verena Huber, on 11 August 1950. They had two children, Esther and George, before divorcing in 1958. In November 1958 he married Imme Jung (born 1936) and they had four more children: Dorothy, Mia, Rebecca, and Emily Dyson.

Dyson's eldest daughter, Esther, is a digital technology consultant and investor; she has been called "the most influential woman in all the computer world". His son George is a historian of science, one of whose books is Project Orion: The Atomic Spaceship 1957–1965.

Dyson died on 28 February 2020 at a hospital near Princeton, New Jersey, from complications following a fall. He was 96.

Biotechnology and genetic engineering
Dyson admitted his record as a prophet was mixed, but thought it is better to be wrong than vague, and that in meeting the world's material needs, technology must be beautiful and cheap.

"My book The Sun, the Genome, and the Internet (1999) describes a vision of green technology enriching villages all over the world and halting the migration from villages to megacities. The three components of the vision are all essential: the sun to provide energy where it is needed, the genome to provide plants that can convert sunlight into chemical fuels cheaply and efficiently, the Internet to end the intellectual and economic isolation of rural populations. With all three components in place, every village in Africa could enjoy its fair share of the blessings of civilization."

Dyson coined the term "green technologies", based on biology instead of physics or chemistry, to describe new species of microorganisms and plants designed to meet human needs. He argued that such technologies would be based on solar power rather than the fossil fuels whose use he saw as part of what he calls "gray technologies" of industry. He believed that genetically engineered crops, which he described as green, can help end rural poverty, with a movement based in ethics to end the inequitable distribution of wealth on the planet.

The Origin of Life
Dyson favoured the dual origin theory: that life first formed as cells, then enzymes, and finally, much later, genes. This was first propounded by the Russian biochemist, Alexander Oparin. J. B. S. Haldane developed the same theory independently. In Dyson's version of the theory, life evolved in two stages, widely separated in time. Because of the biochemistry, he regards it as too unlikely that genes could have developed fully blown in one process. Current cells contain adenosine triphosphate or ATP and adenosine 5'-monophosphate or AMP, which greatly resemble each other but have completely different functions. ATP transports energy around the cell, and AMP is part of RNA and the genetic apparatus. Dyson proposed that in a primitive early cell containing ATP and AMP, RNA and replication came into existence only because of the similarity between AMP and RNA. He suggested that AMP was produced when ATP molecules lost two of their phosphate radicals, and then one cell somewhere performed Eigen's experiment and produced RNA.

There is no direct evidence for the dual origin theory, because once genes developed, they took over, obliterating all traces of the earlier forms of life. In the first origin, the cells were probably just drops of water held together by surface tension, teeming with enzymes and chemical reactions, and having a primitive kind of growth or replication. When the liquid drop became too big, it split into two drops. Many complex molecules formed in these "little city economies" and the probability that genes would eventually develop in them was much greater than in the prebiotic environment.

Dyson sphere
In 1960 Dyson wrote a short paper for the journal Science titled "Search for Artificial Stellar Sources of Infrared Radiation". In it he speculated that a technologically advanced extraterrestrial civilization might surround its native star with artificial structures to maximize the capture of the star's energy. Eventually, the civilization would enclose the star, intercepting electromagnetic radiation with wavelengths from visible light downward and radiating waste heat outward as infrared radiation. One method of searching for extraterrestrial civilizations would be to look for large objects radiating in the infrared range of the electromagnetic spectrum.

"One should expect that, within a few thousand years of its entering the stage of industrial development, any intelligent species should be found occupying an artificial biosphere which surrounds its parent star."

Dyson conceived that such structures would be clouds of asteroid-sized space habitats, though science fiction writers have preferred a solid structure: either way, such an artifact is often called a Dyson sphere, although Dyson used the term "shell". Dyson said that he used the term "artificial biosphere" in the article to mean a habitat, not a shape. The general concept of such an energy-transferring shell had been created decades earlier by science fiction writer Olaf Stapledon in his 1937 novel Star Maker, a source which Dyson credited publicly.

Dyson tree
Dyson also proposed the creation of a Dyson tree, a genetically engineered plant capable of growing inside a comet. He suggested that comets could be engineered to contain hollow spaces filled with a breathable atmosphere, thus providing self-sustaining habitats for humanity in the outer Solar System.

"Plants could grow greenhouses… just as turtles grow shells and polar bears grow fur and polyps build coral reefs in tropical seas. These plants could keep warm by the light from a distant Sun and conserve the oxygen that they produce by photosynthesis. The greenhouse would consist of a thick skin providing thermal insulation, with small transparent windows to admit sunlight. Outside the skin would be an array of simple lenses, focusing sunlight through the windows into the interior… Groups of greenhouses could grow together to form extended habitats for other species of plants and animals."

Space colonies
"I've done some historical research on the costs of the Mayflower's voyage, and on the Mormons' emigration to Utah, and I think it's possible to go into space on a much smaller scale. A cost on the order of $40,000 per person [1978 dollars, $181,600 in 2022 dollars] would be the target to shoot for; in terms of real wages, that would make it comparable to the colonization of America. Unless it's brought down to that level it's not really interesting to me, because otherwise, it would be a luxury that only governments could afford."

Dyson was interested in space travel since he was a child, reading such science fiction classics as Olaf Stapledon's Star Maker. As a young man, he worked for General Atomics on the nuclear-powered Orion spacecraft. He hoped Project Orion would put men on Mars by 1965, and Saturn by 1970. For a quarter-century, Dyson was unhappy about how the government conducted space travel: "The problem is, of course, that they can't afford to fail. The rules of the game are that you don't take a chance, because if you fail, then probably your whole program gets wiped out."

Dyson still hoped for cheap space travel, but was resigned to waiting for private entrepreneurs to develop something new and inexpensive.

"No law of physics or biology forbids cheap travel and settlement all over the solar system and beyond. But it is impossible to predict how long this will take. Predictions of the dates of future achievements are notoriously fallible. My guess is that the era of cheap unmanned missions will be the next fifty years, and the era of cheap manned missions will start sometime late in the twenty-first century.

Any affordable program of manned exploration must be centred in biology, and its time frame tied to the time frame of biotechnology; a hundred years, roughly the time it will take us to learn to grow warm-blooded plants, is probably reasonable."

Space exploration
"A direct search for life in Europa's ocean would today be prohibitively expensive. Impacts on Europa give us an easier way to look for evidence of life there. Every time a major impact occurs on Europa, a vast quantity of water is splashed from the ocean into the space around Jupiter. Some of the water evaporates, and some condenses into snow. Creatures living in the water far enough from the impact have a chance of being splashed intact into space and quickly freeze-dried. Therefore, an easy way to look for evidence of life in Europa's ocean is to look for freeze-dried fish in the ring of space debris orbiting Jupiter.

Freeze-dried fish orbiting Jupiter is a fanciful notion, but nature in the biological realm has a tendency to be fanciful. Nature is usually more imaginative than we are. …To have the best chance of success, we should keep our eyes open for all possibilities."

Dyson's eternal intelligence
Dyson proposed that an immortal group of intelligent beings could escape the prospect of heat death by extending time to infinity while expending only a finite amount of energy. This is also known as the Dyson scenario.

Dyson's transform
His concept "Dyson's transform" led to one of the most important lemmas of Olivier Ramaré's theorem: that every even integer can be written as a sum of no more than six primes.

Dyson series
The Dyson series, the formal solution of an explicitly time-dependent Schrödinger equation by iteration, and the corresponding Dyson time-ordering operator $$\mathcal T\,,$$ an entity of basic importance in the mathematical formulation of quantum mechanics, are also named after Dyson.

Quantum physics and prime numbers
Dyson and Hugh Montgomery discovered an intriguing connection between quantum physics and Montgomery's pair correlation conjecture about the zeros of the zeta function. The primes 2, 3, 5, 7, 11, 13, 17, 19,... are described by the Riemann zeta function, and Dyson had previously developed a description of quantum physics based on m by m arrays of totally random numbers. Montgomery and Dyson discovered that the eigenvalues of these matrices are spaced apart in exactly the same manner as Montgomery conjectured for the nontrivial zeros of the zeta function. Andrew Odlyzko has verified the conjecture on a computer, using his Odlyzko–Schönhage algorithm to calculate many zeros.

There are in nature one, two, and three-dimensional quasicrystals. Mathematicians define a quasicrystal as a set of discrete points whose Fourier transform is also a set of discrete points. Odlyzko has done extensive computations of the Fourier transform of the nontrivial zeros of the zeta function, and they seem to form a one-dimensional quasicrystal. This would in fact follow from the Riemann hypothesis.

Rank of a partition

In number theory and combinatorics, the rank of an integer partition is a certain integer associated with the partition. Dyson introduced the concept in a paper published in the journal Eureka. It was presented in the context of a study of certain congruence properties of the partition function discovered by the mathematician Srinivasa Ramanujan.

Crank of a partition
In number theory, the crank of a partition is a certain integer associated with the partition. Dyson first introduced the term without a definition in a 1944 paper in a journal published by the Mathematics Society of Cambridge University. He then gave a list of properties this yet-to-be-defined quantity should have. In 1988, George E. Andrews and Frank Garvan discovered a definition for the crank satisfying the properties Dyson had hypothesized.

Astrochicken

Astrochicken is the name given to a thought experiment Dyson expounded in his book Disturbing the Universe (1979). He contemplated how humanity could build a small, self-replicating automaton that could explore space more efficiently than a crewed craft could. He attributed the general idea to John von Neumann, based on a lecture von Neumann gave in 1948 titled The General and Logical Theory of Automata. Dyson expanded on von Neumann's automata theories and added a biological component.

Lumpers and splitters
Dyson suggested that philosophers can be broadly if simplistically, divided into lumpers and splitters. These roughly correspond to Platonists, who regard the world as made up of ideas, and materialists, who imagine it divided into atoms.

Climate change
Dyson agreed that technically humans and additional CO$2$ emissions contribute to warming. However, he felt that the benefits of additional CO$2$ outweighed any associated negative effects. He said that in many ways increased atmospheric carbon dioxide is beneficial, and that it is increasing biological growth, agricultural yields and forests. He believed that existing simulation models of climate change fail to account for some important factors, and that the results thus contain too great a margin of error to reliably predict trends. He argued that political efforts to reduce the causes of climate change distract from other global problems that should take priority, and viewed the acceptance of climate change as comparable to religion.

In 2009, Dyson criticised James Hansen's climate-change activism. "The person who is really responsible for this overestimate of global warming is Jim Hansen. He consistently exaggerates all the dangers... Hansen has turned his science into ideology." Hansen responded that Dyson "doesn't know what he's talking about... If he's going to wander into something with major consequences for humanity and other life on the planet, then he should first do his homework- which he obviously has not done on global warming". Dyson replied that "[m]y objections to the global warming propaganda are not so much over the technical facts, about which I do not know much, but it's rather against the way those people behave and the kind of intolerance to criticism that a lot of them have." Dyson stated in an interview that the argument with Hansen was exaggerated by The New York Times, stating that he and Hansen are "friends, but we don't agree on everything."

Since originally taking an interest in climate studies in the 1970s, Dyson suggested that carbon dioxide levels in the atmosphere could be controlled by planting fast-growing trees. He calculated that it would take a trillion trees to remove all carbon from the atmosphere. In a 2014 interview he said, "What I'm convinced of is that we don't understand climate… It will take a lot of very hard work before that question is settled."

Dyson was a member of the academic advisory council of the Global Warming Policy Foundation.

Warfare and weapons
At RAF Bomber Command, Dyson and colleagues proposed removing two gun turrets from Avro Lancaster bombers, to cut the catastrophic losses due to German fighters in the Battle of Berlin. A Lancaster without turrets could fly 50 mph faster and be much more manoeuvrable.

"All our advice to the commander in chief [went] through the chief of our section, who was a career civil servant. His guiding principle was to tell the commander in chief things that the commander in chief liked to hear… To push the idea of ripping out gun turrets, against the official mythology of the gallant gunner defending his crew mates… was not the kind of suggestion the commander in chief liked to hear."

On hearing the news of the bombing of Hiroshima:

"I agreed emphatically with Henry Stimson. Once we had got ourselves into the business of bombing cities, we might as well do the job competently and get it over with. I felt better that morning than I had felt for years… Those fellows who had built the atomic bombs obviously knew their stuff… Later, much later, I would remember [the downside]."

"I am convinced that to avoid nuclear war it is not sufficient to be afraid of it. It is necessary to be afraid, but it is equally necessary to understand. And the first step in understanding is to recognize that the problem of nuclear war is basically not technical but human and historical. If we are to avoid destruction we must first of all understand the human and historical context out of which destruction arises."

In 1967, in his capacity as a military adviser, Dyson wrote an influential paper on the issue of possible US use of tactical nuclear weapons in the Vietnam War. When a general said in a meeting, "I think it might be a good idea to throw in a nuke now and then, just to keep the other side guessing…" Dyson became alarmed and obtained permission to write a report on the pros and cons of using such weapons from a purely military point of view. (This report, Tactical Nuclear Weapons in Southeast Asia, published by the Institute for Defense Analyses, was obtained, with some redactions, by the Nautilus Institute for Security and Sustainability under the Freedom of Information act in 2002.) It was sufficiently objective that both sides of the debate based their arguments on it. Dyson says that the report showed that, even from a narrow military point of view, the US was better off not using nuclear weapons.

Dyson opposed the Vietnam War, the Gulf War and the invasion of Iraq. He supported Barack Obama in the 2008 US presidential election and The New York Times described him as a political liberal. He was one of 29 leading US scientists who wrote Obama a strongly supportive letter about his administration's 2015 nuclear deal with Iran.

Science and religion
Dyson was raised in what he described as a "watered-down Church of England Christianity". He was a nondenominational Christian and attended various churches, from Presbyterian to Roman Catholic. Regarding doctrinal or Christological issues, he said, "I am neither a saint nor a theologian. To me, good works are more important than theology."

"Science and religion are two windows that people look through, trying to understand the big universe outside, trying to understand why we are here. The two windows give different views, but they look out at the same universe. Both views are one-sided, and neither is complete. Both leave out essential features of the real world. And both are worthy of respect.

Trouble arises when either science or religion claims universal jurisdiction when either religious or scientific dogma claims to be infallible. Religious creationists and scientific materialists are equally dogmatic and insensitive. By their arrogance, they bring both science and religion into disrepute. The media exaggerate their numbers and importance. The media rarely mention the fact that the great majority of religious people belong to moderate denominations that treat science with respect or the fact that the great majority of scientists treat religion with respect so long as religion does not claim jurisdiction over scientific questions."

Dyson partially disagreed with the remark by his fellow physicist Steven Weinberg that "With or without religion, good people can behave well and bad people can do evil; but for good people to do evil – that takes religion."

"Weinberg's statement is true as far as it goes, but it is not the whole truth. To make it the whole truth, we must add an additional clause: 'And for bad people to do good things – that [also] takes religion.' The main point of Christianity is that it is a religion for sinners. Jesus made that very clear. When the Pharisees asked his disciples, 'Why eateth your Master with publicans and sinners?' he said, 'I come to call not the righteous but sinners to repentance.' Only a small fraction of sinners repent and do good things but only a small fraction of good people are led by their religion to do bad things."

Dyson identified himself as agnostic about some of the specifics of his faith. For example, in reviewing The God of Hope and the End of the World by John Polkinghorne, Dyson wrote:

"I am myself a Christian, a member of a community that preserves an ancient heritage of great literature and great music, provides help and counsel to young and old when they are in trouble, educates children in moral responsibility, and worships God in its own fashion. But I find Polkinghorne's theology altogether too narrow for my taste. I have no use for a theology that claims to know the answers to deep questions but bases its arguments on the beliefs of a single tribe. I am a practicing Christian but not a believing Christian. To me, to worship God means to recognize that mind and intelligence are woven into the fabric of our universe in a way that altogether surpasses our comprehension."

In The God Delusion (2006), evolutionary biologist and atheist activist Richard Dawkins singled out Dyson for accepting the Templeton Prize in 2000: "It would be taken as an endorsement of religion by one of the world's most distinguished physicists." In 2000, Dyson declared that he was a (non-denominational) Christian, and he disagreed with Dawkins on several subjects, such as that group selection is less important than individual selection on the subject of evolution.

Named after Dyson

 * Dyson conjecture
 * Dyson equation
 * Dyson numbers
 * Dyson operator
 * Dyson series
 * Dyson sphere
 * Dyson tree
 * Dyson's crank
 * Dyson's eternal intelligence
 * Dyson's transform
 * Dyson–Maleev spin wave theory
 * Schwinger–Dyson equation
 * Thue–Siegel–Dyson–Roth theorem
 * Feynman diagram, also known as Dyson graphs
 * Wigner–Yamase–Dyson conjecture
 * Gordon Freeman, a fictional character named after Dyson

Honors and awards

 * Dyson was elected a Fellow of the Royal Society (FRS) in 1952.
 * Dyson was elected to the American Academy of Arts and Sciences in 1958.
 * Dyson was elected to the United States National Academy of Sciences in 1964.
 * Dyson was awarded the Dannie Heineman Prize for Mathematical Physics in 1965, Lorentz Medal in 1966, Max Planck Medal in 1969, the J. Robert Oppenheimer Memorial Prize in 1970, the Harvey Prize in 1977 and Wolf Prize in 1981.
 * Dyson was elected to the American Philosophical Society in 1976.
 * In 1986, Dyson received the Golden Plate Award of the American Academy of Achievement.
 * In 1989, Dyson was elected as an Honorary Fellow of Trinity College, University of Cambridge.
 * In 1990, Dyson taught at Duke University as a Fritz London Memorial Lecturer.
 * Dyson published a number of collections of speculations and observations about technology, science, and the future. In 1996, he was awarded the Lewis Thomas Prize for Writing about Science.
 * In 1993, Dyson was given the Enrico Fermi Award.
 * In 1995, he gave the Jerusalem-Harvard Lectures at the Hebrew University of Jerusalem, sponsored jointly by the Hebrew University and Harvard University Press that grew into the book Imagined Worlds.
 * In 2000, Dyson was awarded the Templeton Prize for Progress in Religion.
 * In 2003, Dyson was awarded the Telluride Tech Festival Award of Technology in Telluride, Colorado.
 * In 2011, Dyson received as one of twenty distinguished Old Wykehamists at the Ad Portas celebration, the highest honor that Winchester College bestows.
 * In 2011, Dyson received the Arthur C. Clarke Lifetime Achievement Award from the Arthur C. Clarke Foundation.
 * In 2018, Dyson received the first Presidential Science and Humanism Award from the American University of Beirut.

Publications

 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * (Winner of the National Book Critics Circle Award).
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.
 * A formerly secret document, declassified December 2002.

Documentaries

 * To Mars by A-Bomb: The Secret History of Project Orion
 * The Oakes
 * Atomic Dream
 * 2001: The Science of Futures Past
 * Cool It
 * Nuclear Dynamite
 * Gaia Symphony III
 * The Starship and the Canoe
 * The Day After Trinity
 * The Untold History of the United States
 * The Uncertainty Has Settled
 * A Glorious Accident
 * Freeman Dyson: Space Dreamer

By Dyson

 * Freeman Dyson at The New York Review of Books (content for subscribers only)
 * "Heretical thoughts about science & society", essay by Freeman Dyson [8.7.2007]
 * Templeton Prize acceptance lecture 2000, by Freeman Dyson
 * Imagined Worlds by Freeman Dyson, 1996: Chapter 1
 * A radio interview with Freeman Dyson Aired on the Lewis Burke Frumkes Radio Show in 2009.
 * Suzan Mazur interviewing Dyson, 2012, CounterPunch
 * "Pushing the Boundaries – A Conversation with Freeman Dyson", Ideas Roadshow, 2014
 * , Arthur C. Clarke Center for Human Imagination, February 2019.
 * A ‘Rebel’ Without a Ph.D.
 * A ‘Rebel’ Without a Ph.D.

About Dyson

 * "Freeman Dyson's Brain", interview by Stewart Brand at Wired, 1998
 * 2008 Video Interview with Freeman Dyson by Atomic Heritage Foundation, Voices of the Manhattan Project
 * Remembering the Unstoppable Freeman Dyson
 * Freeman J. Dyson, a Biographical Memoir by Ann Finkbeiner and William H. Press.
 * Remembering the Unstoppable Freeman Dyson
 * Freeman J. Dyson, a Biographical Memoir by Ann Finkbeiner and William H. Press.
 * Freeman J. Dyson, a Biographical Memoir by Ann Finkbeiner and William H. Press.

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

title: Freeman Dyson


text:
Fourth Council of the Lateran

The Fourth Council of the Lateran or Lateran IV was convoked by Pope Innocent III in April 1213 and opened at the Lateran Palace in Rome on 11 November 1215. Due to the great length of time between the council's convocation and its meeting, many bishops had the opportunity to attend this council, which is considered by the Catholic Church to be the twelfth ecumenical council. The council addressed a number of issues, including the sacraments, the role of the laity, the treatment of Jews and heretics, and the organization of the church.

In the case of Jews and Muslims, this included compelling them to wear distinctive badges to prevent social contact "through error". The Council is viewed by medievalists as both opening up many reforms, and as formalising and enforcing intolerance in European society, both to heretics and Jews, and thus playing a role in the development of systemic European antisemitism.

Background
Innocent III first mooted organizing an ecumenical council in November 1199. In his letter titled Vineam Domini, dated 19 April 1213, the Pope writes of the urgent need to recover the Holy Land and reform the Church. The letter, which also served as a summons to an ecumenical council, was included alongside the Pope's papal bull Quia maior. In preparing for the council, the Pope spearheaded the extensive refurbishment of the old St. Peter's Basilica, which he designated as the "centrepiece for display and decoration" during the council. The lunette of the main door leading to the tomb of St. Peter had engravings of Old Testament prophets and twenty-four bishops, alongside the messages, "Feed your Sheep" and "This is the Door of the Sheep".

The measures against the Jews were the culmination of hostility during Innocent's reign as Pope, itself informed by a background of greater hostility to the Jews generated in part by the Crusades. Innocent for example waged a novel campaign against the Talmud as part of the campaign against heresy, claiming that the Talmud was an invention of the Rabbis, and the Jews should be restricted to using Biblical texts for their faith. This was the first time that the Catholic church had tried to directly regulate the practice of Judaism.

Proceedings
Innocent III deliberately chose for the Fourth Council to meet in November, during which there were numerous feast days. A preliminary legal session took place on 4 November, while the opening ceremony of the council was held on St. Martin's Day and began with a private morning Mass. Afterwards, at the start of the first plenary session in the Lateran Palace, the Pope led the singing of "Veni Creator Spiritus" and preached about Jesus' words to his disciples at the Last Supper, quoting from Luke 22. In his next two sermons, one on the need to recover the Holy Land and the other on dealing with heretics, the Pope was joined on stage by Raoul of Mérencourt and Thedisius of Agde respectively.

On 14 November, there were violent scenes between the partisans of Simon de Montfort among the French bishops and those of the Count of Toulouse. Raymond VI of Toulouse, his son (afterwards Raymond VII), and Raymond-Roger of Foix attended the council to dispute the threatened confiscation of their territories; Bishop Foulques and Guy de Montfort (brother of Simon de Montfort) argued in favour of the confiscation. All of Raymond VI's lands were confiscated, save Provence, which was kept in trust to be restored to Raymond VII. Pierre-Bermond of Sauve's claim to Toulouse was rejected and Toulouse was awarded to de Montfort, while the lordship of Melgueil was separated from Toulouse and entrusted to the bishops of Maguelonne.

The next day, in a ceremony attended by many council participants, the Pope consecrated the Basilica of Santa Maria in Trastevere, which had been rebuilt by Callixtus II. Four days later, the anniversary celebration at St. Peter's Basilica brought together such a large gathering that the Pope himself had trouble entering the premises.

The second plenary session was held on 20 November; the Pope was scheduled to preach about church reform, but proceedings were disrupted by bishops who opposed the designation of Frederick II as Holy Roman Emperor. The council concluded on 30 November, Saint Andrew's Day, during which the Pope preached on the Nicene Creed and concluded his remarks by raising up a relic of the True Cross. The archbishop of Mainz attempted to interrupt the speech, although he complied with the Pope's raising of his handa command to stay silent.

Outcomes
Lateran IV had three objectives: crusading, Church reform, and combating heresy. The seventy-one Lateran canons, which were not debated, were only formally adopted on the last day of the council; according to Anne J. Duggan, the "scholarly consensus" is that they were drafted by Innocent III himself. They cover a range of themes including Church reform and elections, taxation, matrimony, tithing, simony, and Judaism. After being recorded in the papal registers, the canons were quickly circulated in law schools. Effective application of the decrees varied according to local conditions and customs.

Machinery of enforcement
While the precise application and levels of conformity to Lateran IV were variable, it is argued that it created a wide range of legal measures with long term repercussions, which were used to persecute minorities and helped usher in a specifically intolerant kind of European society, or as historian R. I. Moore defines it, a "persecuting society". These measures applied with vigour first to heretics, and then increasingly to other minorities, such as Jews and lepers. In the case of Jews, antisemitism had been rising since the Crusades in different parts of Europe, and the measures of Lateran IV gave the legal means to implement active systemic persecution, such as physical separation of Jews and Christians, enforced through Jews being obliged to wear distinctive badges or clothing.

Jewish badges
The Council mandated that Jews separate and distinguish themselves, in order to "protect" Christians from their influence. "In some provinces a difference in dress distinguishes the Jews or Saracens from the Christians, but in certain others such a confusion has grown up that they cannot be distinguished by any difference. Thus it happens at times that through error Christians have relations with the women of Jews or Saracens, and Jews and Saracens with Christian women. Therefore, that they may not, under pretext of error of this sort, excuse themselves in the future for the excesses of such prohibited intercourse, we decree that such Jews and Saracens of both sexes in every Christian province and at all times shall be marked off in the eyes of the public from other peoples through the character of their dress. Particularly, since it may be read in the writings of Moses [], that this very law has been enjoined upon them."

Records and implementation
While the proceedings were not officially recorded, unlike in previous councils, evidence of the events have been found in various manuscripts by observers of the council. The Chronica Majora by Matthew Paris contains a line drawing of one of the sessions at the council which his abbot William of St Albans had personally attended. An extensive eyewitness account by an anonymous German cleric was copied into a manuscript that was published in 1964, in commemoration of the Second Vatican Council, and is now housed at the University of Giessen.

Dissemination of the Canons themselves was often patchy and incomplete, as it relied on handwritten records kept by local bishops, while it is unclear if the Papacy ever provided official copies. Local adaptations of the Canons could reflect disagreements or differences of priorities, and the incompleteness of the transmission of the canons was recognised as a significant problem by the Papacy. Implementation of the Council's reforms was included within the Canons, with instructions that local councils should be held in order to create plans for their adoption. Provinces held councils to instruct Bishops to hold local synods, however the evidence suggests that this mechanism did not result in Bishops holding meetings and organising reforms in the manner intended.

Legacy
Henry of Segusio likened the council to the "four great councils of antiquity". Lateran IV is sometimes referred to as the "Great Council of the Lateran" due to the presence of 404 or 412 bishops (including 71 cardinals and archbishops) and over 800 abbots and priors representing some eighty ecclesiastical provinces, together with 23 Latin-speaking prelates from the Eastern Orthodox Church and representatives of several monarchs, including Frederick II, Otto IV, the Latin Emperor of Constantinople, John, King of England, Andrew II of Hungary, Philip II of France, and the kings of Aragon, Cyprus, and Jerusalem. This made it the largest ecumenical council between the Council of Chalcedon and the Second Vatican Council; Anne J. Duggan writes that "it was the largest, most representative, and most influential council assembled under papal leadership before the end of the fourteenth century." According to F. Donald Logan, "the Fourth Lateran Council was the most important general council of the church in the Middle Ages", whose effects "were felt for centuries."

title: Fourth Council of the Lateran


text:
Talk:French Republican calendar

1800 not a Gregorian leap year
Does that cause something to be knocked a day off? The French Revolurionary calendar started in 1792, and Gregorian wasn't officially restored until 1806. Carlm0404 (talk) 07:24, 17 December 2021 (UTC)

 * This has gone unanswered for over a year, and likely won’t be read, but the answer is that the Republican Calendar is independent of the Georgian, so the leap years, or lack thereof, in one calendar have no effect on the other. —Nike (talk) 12:30, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 5h 26m t.m.P.)

Elvish
Is it worth mentioning, under "cultural references", that most of the Elvish month names given by Tolkien in Appendix B are translations of the Republican names? But perhaps it's coincidental. —Tamfang (talk) 18:18, 14 January 2023 (UTC)

 * I guess not, that's OR/synthesis. —Tamfang (talk) 22:54, 14 January 2023 (UTC)
 * I’d say not OR/synthesis, it has been described and discussed in Jim Allan (ed.) (1978), An Introduction to Elvish, p. 151. — Mithrennaith (talk) 11:31, 6 March 2023 (UTC)

Lead mentions religious reasons, source, discussion in body?
Doug Weller talk 19:26, 12 February 2023 (UTC)
 * I'm not sure what this talk section is for/ about. It would seem to be suggesting that the reasons for the new calendar replacing a religious one are not present in the body of the article, but the Rural calender section in the article specifically talks of the calendar in a religious context:
 * https://en.wikipedia.org/wiki/French_Republican_calendar#Rural_calendar
 * "The Catholic Church used a calendar of saints, which named each day of the year after an associated saint. To reduce the influence of the Church, Fabre d'Églantine introduced a Rural Calendar in which each day of the year had a unique name associated with the rural economy, stated to correspond to the time of year"

I'm not sure how this could be any clearer. If you still see a problem with this being described as 'partly for religous reasons' please expand on your argument, please spell it out because I really do not see what possible objection you can have here!! Scarabocchio (talk) 15:33, 14 February 2023 (UTC)
 * does this answer your point??? Scarabocchio (talk) 19:23, 13 February 2023 (UTC)
 * @Scarabocchio that happened but the section doesn’t say it was a reason for the change. It was something done after the new calendar so far as I know. Doug Weller  talk 20:27, 13 February 2023 (UTC)
 * The section seems quite clear to me .. the principle that informed and guided the design, as stated by one of the key persons to implement it, was to reduce the influence of the Church. "The priests assigned the commemoration of a so-called saint to each day of the year: this catalogue exhibited neither utility nor method; it was a collection of lies, of deceit or of charlatanism. We thought that the nation, after having kicked out this canonised mob from its calendar, must replace it with the objects that make up the true riches of the nation. ... So we have arranged in the column of each month, the names of the real treasures of the rural economy."
 * @Doug Weller Please keep your replies in this section so we can have a dialogue. My comment above explains clearly why there was a religious component to the decision of how the new calendar was implemented. Whether other predecessor concepts didn't have the religious component that the FRC did is irrelevent. The actual FRC did, and we have the actual words of one of the primary creators of the calendar explictly stating this. I have not, yet, seen anything at all from you to explain why you think that this can be set aside. Scarabocchio (talk) 16:07, 14 February 2023 (UTC)

Does nobody know about Google? http://prairial.free.fr/index.php?lien=cal_presenatusconsulte1805 https://gallica.bnf.fr/ark:/12148/bpt6k6438979z.texteImage https://gallica.bnf.fr/ark:/12148/bpt6k487479.image —Nike (talk) 09:50, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 4h 16m t.m.P.)

 * @Nike Have you read my posts below? They're the result of Google searches. Thanks though, that's interesting. Doug Weller  talk 10:06, 15 February 2023 (UTC)

 * There is nothing wrong with using Google to find sources. The tool used is irrelevant, so long as the sourced are valid. I linked to original sources. I posted links to Gallica. There’s another at JSTOR. What is wrong with these? The French Wikipedia also gives some sources. To keep deleting sourced material is vandalism, and will be treated as such. —Nike (talk) 12:09, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 5h 12m 73s t.m.P.)

 * @Nike Not a good idea to call a content dispute vandalism. It's not. I use Google all the time for sources. You still haven't read what I've said. We need sources explicitly linking a religious motivation and have none. But if you'd read what I wrote below you'd know I seem to have found one. using Google.  Doug Weller  talk 12:14, 15 February 2023 (UTC)
 * And if you’d look at the sources given, you will clearly see that they explicitly state what is disputed. It was not hard to find. There is no good reason to delete it. —-Nike (talk) 13:02, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 5h 49m t.m.P.)
 * @Nike ok, show me a source you've read that makes that link. Recall I'm no longer disputing this but suggesting additions and a clear source. Doug Weller  talk 13:11, 15 February 2023 (UTC)

Just read the sources I provided.

« Il fut imaginé dans la vue de donner aux Français un calendrier purement civil, et qui, n'étant subordonné aux pratiques d'aucun culte, convînt également à tous. »

« Cette distribution qui, ne concordant avec les cultes d’aucune secte, déroute les gens superstitieux, écarte les préjugés, est la plus convenable à une nation qui veut tolérer toutes les religions, sans permettre pour aucune des pratiques extérieures. »

« Cette opération faite, les moyens de la consolider seront de tenir strictement la main à ce que la superstition rusée n’abuse point, par leur application trop étendue, des principes consacrés par la dernière loi sur la liberté des cultes, et pour cela il faut avoir grand soin d’établir des fêtes décadaires, et de faire concorder les jours de foires et de marchés avec le nouveau calendrier. »

«La loi sur la liberté des cultes n’en tolère l’exercice que dans des lieux particuliers 3. Si on laissait la faculté de louer les anciens temples pour les employer à cet usage 4, le culte reprendrait inévitablement un caractère de publicité qu’il ne faut pas permettre, et cette attention est trop importante, pour fermer les yeux sur les suites dangereuse de l’apathie ou de l’excessive tolérance. »

—Nike (talk) 14:56, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 6h 28m décimales t.m.P.)

 * I found a good source, albeit not contemporary.
 * Les séquelles de la déchristianisation de l'an II : l'héritage laïc sous le Consulat et l'Empire
 * Xavier Maréchaux
 * Dans Napoleonica. La Revue 2012/3 (N° 15),
 * --Nike (talk) 16:17, 15 February 2023 (UTC) (Décade III Sextidi 26 Pluviôse an CCXXXI à 6h 84m t.m.P.)
 * How about my sources? Doug Weller  talk 16:36, 15 February 2023 (UTC)
 * And as I said, it’s not enough to add it to the lead, we should have a section on the motivations to comply with WP:LEAD. Doug Weller  talk 19:34, 15 February 2023 (UTC)
 * We don’t need a new section, just something in an existing section, such as “History.” But do as you wish. You might want to mention the intent of décadis and revolutionary holidays to replace Sundays and Catholic holidays. They even tried to make a new religion around décadis. In the years VII and VIII, marriages could only be conducted on décadis .People were supposed to name their children after calendar days, instead of saints. E.g., a girl born on this day might be named Hazel. Of course, under Napoleon all this reversed so as to reinstall the Church. —Nike (talk) 00:13, 16 February 2023 (UTC) (Décade III Septidi 27 Pluviôse l’an CCXXXI à 14m t.m.P., jour du noisetier.)
 * I'm not doing anything - as I'm dying too soon I'm working on articles of more interest. And I do believe that we need to use English sources where possible as most of our readers won't read French (you know I imagine how bad English speaking countries are with other languages). And I've provided those sources below. Doug Weller  talk 09:46, 16 February 2023 (UTC)
 * Well, it is the French calendar. Most of my sources go back to the Revolution. But they’re ready to read in Google translate. I would, of course, use English translations in the text of the article.
 * "The law on freedom of worship tolerates its exercise only in particular places. If we left the faculty of renting the old temples to use them for this purpose, worship would inevitably regain a public character that should not be allowed, and this attention is too important, to close our eyes to the dangerous consequences of apathy or excessive tolerance.”
 * —Nike (talk) 21:15, 16 February 2023 (UTC) (Décade III Septidi 27 Pluviôse l‘an CCXXXI à 8h 91m décimales t.m.P.)
 * How about https://www.cairn-int.info/journal-napoleonica-la-revue-2012-3-page-4.htm
 * —Nike (talk) 21:29, 16 February 2023 (UTC) (Décade III Septidi 27 Pluviôse l‘an CCXXXI à 9h 1m décimales t.m.P.)

 * - Secularization: its goal is to eradicate Christian references in French society. This process takes several forms: substitution of the republican calendar with the Gregorian calendar, establishment of a new civil status held by mayors and no longer the parish priests, change of place names with the main purpose of removing Christian and feudal references, use of revolutionary first names without reference to the saints of the Gregorian calendar, secular education removed from the hands of the clergy.
 * (Décade III Septidi 27 Pluviôse l‘an CCXXXI à 9h 7m 69s décimales t.m.P.) Nike (talk) 21:38, 16 February 2023 (UTC)
 * According to Alphonse Aulard, the establishment of the Republican calendar in October 1793 was "the most anti-Christian measure" of the Convention [13]. Richard Cobb outbids by seeing the new calendar as a "sensational innovation" that constitutes an attack on the customs and habits of the French and an attempt to destroy Catholicism [14]. It is true that if the presentation of the republican calendar is part of the effort to rationalize the weights and measures inherited from the Ancien Régime - such as the implementation of the meter, kilogram and liter - also using a decimal system, the abolition of the week (and therefore Sunday) as well as the replacement of saints with names of "objects that make up true national wealth [15]", have the effect of removing any Christian reference in the measure of time.
 * —Nike (talk) 21:57, 16 February 2023 (UTC) (Décade III Septidi 27 Pluviôse l‘an CCXXXI à 9h 20m 87s décimales t.m.P.)
 * The body of the article describes not only the abolition of saints days, which should have been sufficient, but also of the Christian era, Sundays and religious holidays. Is that not enough?
 * (Décade III Octidi 28 Pluviôse l‘an CCXXXI à 3h 32m 86s décimales t.m.P.)
 * Nike (talk) 07:50, 17 February 2023 (UTC)
 * ok, taking this off my watch list.  Doug Weller  talk 09:36, 17 February 2023 (UTC)
 * How about this source? Revolutionary first names in Dordogne
 * 19 Ventôse year CCXXXI, chervil day @ 4h 88m 22s PMT Nike (talk) 11:36, 10 March 2023 (UTC)

Also see this about Sylvain Marechal's Almanach des Honnetes Gens which the government rejected as anti-religious
"Among these almanacs the most significant was Sylvain Marechal's Almanach des Honnetes Gens, published in I788.4 It contained the real germ of the Republican Calendar. Here appeared the year of twelve equal months with five or six complementary days (scattered through the year, however, instead of all coming together at the end), and each month divided into three decades. But the most startling innovation, at least to contemporaries, was the substitution of " hon- netes gens" for the saints of the Gregorian Calendar. The work was roundly denounced by the government, which ordered it " torn up and burned. . . as impious, sacrilegious, blasphemous, and tending to destroy religion". Such drastic action may have been some- what responsible for later almanacs being less radical, but it did not stop their publication. Since their propagandic value was soon rceognized by the Revolutionary leaders, the number increased.

In I79I the Jacobin Club offered a prize of twenty-five louis for the best patriotic almanac. Forty-two works were submitted to the judges and the prize was won by Collot d'Herbois with his Almanach du Pe're Gerard.6 The award to Collot, however, revealed the note- worthy fact that even among the Jacobins of I79I, anti-religious sentiment was not yet predominant, for his almanac retained the saints' days of the old calendar."

let's discuss, not just revert. Doug Weller talk 15:53, 14 February 2023 (UTC)

 * I think I've found a source which should make you happy but have no time to do it today. If you have JSTOR access it is Making the Revolutionary Calendar Author(s): George Gordon Andrews Source: The American Historical Review, Apr., 1931, Vol. 36, No. 3 (Apr., 1931), pp. 515- 532. Doug Weller  talk 15:56, 14 February 2023 (UTC)

 * Please keep your replies in the main thread Scarabocchio (talk) 16:13, 14 February 2023 (UTC)
 * @Scarabocchio that ship has sailed, it wouldn't make sense for me to comment on material in this thread by posting in another thread. Do you agree that the material I've quoted here needs to be in someway in the article?  Doug Weller  talk 16:52, 14 February 2023 (UTC)
 * I don't think I can quote more due to copyright issues, but the article basically concludes by saying that the majority of the people didn't want a change but a "group" of zealots motivated by a desire for a more logical system and wanting to at least reduce the influence of Christianity got it adopted. Your problem seems to be an attempt to use logic to connect the dots but we don't work that way, we need sources explicitly stating that. And this should be in the body of the text with sources, summarised in the lead without sources. Doug Weller  talk 16:52, 14 February 2023 (UTC)

MOS: Present
Is there guidance that explains why this article uses the past tense? Since this calendar can still be calculated and expressed, so never really ceases to be, doesn't MOS: Present mean this article (and related ones) should reflect that? I know there are carve-outs from MOS: Present for certain subjects, so I'm wondering if there is one for calendars that I missed.128.151.71.7 (talk) 13:11, 21 February 2023 (UTC)

 * "Napoleon declared it abolished" in 1805. Sounds pretty past tense to me. It's not in actual use today. Sure, one could calculate dates as though it were still in use, just like one can calculate Gregorian dates before 1583, or Numa Roman dates after 45 BCE, and some Trekkies use stardates. But there isn't even agreement on how Republican dates should be calculated. Originally, dates were counted from the September equinox, but some would prefer the proposed reform of year 3. I have seen at least 3 other proposed methods.
 * --Nike (talk) 08:25, 22 February 2023 (UTC) ( L'an deux cent trente un de la République française une et indivisible le premier tridi le jour trois du mois de Pluviôse à trois heures cinquante six minutes quarante trois secondes décimales du t.m.P. )
 * du le mois? —Tamfang (talk) 17:41, 22 February 2023 (UTC)
 * Pardon moi, I don’t speak French, and I was trying to imitate civil actes from the Revolution. —Nike (talk) 23:26, 22 February 2023 (UTC) ( L'an deux cent trente un de la République française une et indivisible le premier tridi le jour trois du mois de Pluviôse à neuf heures huitante trois minutes cinquante un secondes décimales du t.m.P. )
 * I liked your previous format, eg Septidi 17 Vendémiaire an CCXXIX à 1 heure 25 minutes décimales t.m.P but miss the plants. Today is le jour de la perce-niege (literally, the plant that breaks through the snow), the day of the snowdrop. Climate change apart, how poetic and indicative that is of this time of year! Scarabocchio (talk) 11:31, 23 February 2023 (UTC)
 * You can see the different formats at Calendars — Decimal Time. There are Twitter bots that post the daily flowers.  Nike (talk) 16:57, 23 February 2023 (UTC) ( L'an deux cent trente un de la République française une et indivisible le premier quartidi le jour quatre du mois de Pluviôse à sept heures douze minutes cinquante deux secondes décimales du t.m.P. )
 * I added rural plant days. You can check it any day at Republican Date Happy Spinach Day.
 * L 'an deux cent trente un de la République française une et indivisible le second sextidi le jour seize du mois de Ventôse, le jour de l’Épinard à une heure soixante dix minutes sept secondes décimales du t.m.P. Nike (talk) 01:36, 7 March 2023 (UTC)
 * You are quite mad :-) but you are not alone. See also the Spinach entry, 16 Ventôse, here: User:Scarabocchio/calendar Scarabocchio (talk) 08:27, 7 March 2023 (UTC)
 * You should post daily tweets about them, like 8th other revolutionaries.
 *  Trois heures quatre vingt sept minutes cinquante deux secondes décimales du t.m.P. Nike (talk) 09:11, 7 March 2023 (UTC)
 * There are, alas, too many days without quirky articles. Scarabocchio (talk) 09:26, 7 March 2023 (UTC) / 17 Ventôse (FRC)
 * You should see all the tweets the other revolutionaries post every day. 16 Ventôse year CCXXXI, spinach day @ 7h 18m 91s PMT Nike (talk) 17:08, 7 March 2023 (UTC)
 * I am currently dying inside from Wheezy, Sneezy, Freezy, Slippy, Drippy, Nippy, Showery, Flowery, Bowery, Hoppy, Croppy, and Poppy DragonMaster9817 (talk) 16:33, 3 May 2023 (UTC)
 * Je vous pardonne puisque – ahem. I forgive you because you did not write "d'l'mois" as many ignorant people might do. —Tamfang (talk) 22:43, 23 February 2023 (UTC)

title: Talk:French Republican calendar