EPOCH. A name we give to certain notable events for which the time is exactly or almost exactly known in ancient and modern chronology, and which serve as fixed points for relating other events to them. This word comes from a Greek word that means stop , because the epochs in history are like resting places, and so to speak, stations, where one stops to consider from there at one’s ease what follows and what came before, and to link the events amongst themselves. See what M. Bossuet says on this subject in his discours sur l'Histoire universelle [ Discourse on universal history ]. [1]

The principal epochs of Sacred History, for example, are the creation of the world, the flood, the calling of Abraham, the exit from Egypt, Saul or the Jews governed by kings, the Babylonian captivity, the return from captivity, and the birth of Jesus Christ. The lengths of these different epochs are different, depending on the chronology one sees fit to follow. See Age, Chronology, etc.

Those of ecclesiastical history are Constantine or the peace of the church, the birth of Islam, the schism of the Greeks, the Crusades, the great schism of the West, Lutheranism, etc.

The epochs of the history of France are Clovis, Pepin, and Hugues Capet, the founders of our three dynasties of kings; and in each of these principal epochs we can situate others: for example, after Hugues Capet one can assign various epochs to Saint Louis, to Charles the Wise, [2] to François I, to Henri IV, and to Louis XIV. The same applies to the history of other peoples. See History. See also the article Era. The rule that should be applied for epochs is that they not be too numerous or too few in number. The reason for this is easily sensed. In the first instance, the reader or historian would pause for no good reason at every step; in the second, he would become exhausted at having too much territory to encompass each time. [3]

Epoch is thus properly a time limit or fixed point in time from which the years are counted. See Year.

Nations have different epochs , and that is not surprising: for as there are no reasons based on astronomy to make one preferable to another, the setting of epochs is purely arbitrary. The principal epoch of the Christians is that of the birth or incarnation of Jesus; of the Muslims the Hegira; of the Jews, the creation of the world; of the ancient Greeks, the Olympiads; of the Romans, the foundation of Rome; of the ancient Persians and Syrians, the epoch or the era of Nabonassar. See Incarnation, Hegira, Olympiad, etc.

Familiarity with and use of epochs is a great advantage in chronology. See Chronology.

It is principally in ancient history that the epochs are necessary. The uncertainty of chronology makes it obligatory to hold onto some principal points to create a consistent system for oneself. The different ways of counting years among different peoples contributes to the difficulty of fixing epochs securely.

To reduce the years of one epoch to those of another, in other words to find the year in one that corresponds to a given year in the other, a period of years has been invented that begins before all the known epochs , and which is, in a manner of speaking, their common meeting point: that period is called the Julian period. It is to this period that we reduce all epochs by determining the year of this period where each epoch begins. Thus it remains only to add the proposed year of one epoch to the year of the period that corresponds to the beginning of that epoch , and to subtract from that same proposed year the year of the same period that corresponds to the other epoch : the remainder is the year of this epoch . See Julian period.

The epoch of Jesus Christ or of our Lord is the common epoch of all Europe; it begins with the nativity of the Savior on 25 December, or rather, according to the usual way of counting, with his circumcision on 1 January; but in England it begins with the incarnation or the annunciation of the Virgin on 25 March, nine months before the nativity. See Nativity, Circumcision, Annunciation, etc.

The year of the Julian period corresponding to that of the birth and circumcision of Jesus is generally counted as the year 4713 of this period. Thus the first year of our era corresponds to the 4714 ^th year of the Julian period.

Therefore, first of all, if to a given year of Christ you add 4713, the sum will be the year of the Julian period that equals the proposed year: for example, if to the present year 1755 you add 4713, the sum 6468 will be our present year in the Julian period. Secondly, contrariwise, if you take away 4713 of a given year of the Julian period, the remainder is the current year of Christ. For example, if from the year 6468 of the Julian period you subtract 4755, the remainder will be the current year 1755.

The epoch of the birth of our Lord serves not only to calculate the number of years that have gone by since the beginning of the epoch, but also for calculating those that preceded it.

To find the year of the Julian period corresponding to a given year before Christ you subtract the proposed year from 4714; the remainder will be the corresponding year that you want. Thus you will find that the year 752 before Christ is the year 3956 of the Julian period. Contrariwise, if you subtract a proposed year of the Julian period from 4714, the remainder is the corresponding year before Christ.

The author of the common epoch , or of the method of counting the years since the birth of Christ, is Dionysius Exiguus, Abbot of Rome, Scythian by nationality, who flourished under the empire of Justinian about the year 507; this Dionysius had got the first idea of it from an Egyptian monk named Panodorus. Until then Christians counted the years from the foundation of Rome or by the order of emperors and consuls, or following the other methods of peoples among whom they were living.

This diversity occasioned a great dispute between the churches of the East and West. In order to put an end to it, Dionysius was the first to propose a new form of year and a new general era, both of which were accepted within a few years.

Dionysius began his era with the incarnation, or with the feast commonly called the annunciation of the Virgin. This method is still in use in the countries under the domination of Great Britain, but it is no longer in use anywhere else; in the other European countries we begin the year on the first of January, except in the Roman court, where the epoch of the incarnation is still applied in the date of bulls. See Incarnation.

We must add that in this epoch of Dionysius there is a mistake. It is commonly believed that he put the birth of Christ one year too late, or that Christ was born the winter before the year that Dionysius marks for the conception. But the truth is that this error must be imputed to Bede, who misunderstood Dionysius, and whose interpretation we follow. That is what Father Pétau has very well proven with Dionysius’s own letters. [4] For Dionysius begins his cycle with the year 4712 of the Julian period, but he only begins his epoch in the year 4713, when the common era supposes that Jesus Christ was incarnated.

Thus, the first year of Christ according to the common epoch is the second according to Dionysius’s calculation. Consequently, the present year 1755 should strictly speaking be 1756; some chronologists even maintain that there is an error not of just one year but of two.

It is to this common era that chronologists reduce all the other epochs as to a fixed and determined point. Yet there is none of these epochs that is not a matter of some dispute, such uncertainty is there in the doctrine of times. [5] We shall now relate the principle epochs reduced to the Julian period.

The epoch of the creation, orbis conditi , [6] also called the Jewish epoch , is, according to the calculation of the Jews, the year 953 of the Julian period, corresponding to the year 3761 B.C., and begins on the 7 ^th of October.

Thus, if you take 952 years from a given year of the Julian period, the remainder will be the year of the Jewish epoch corresponding to it. For example, the present year, being the 6459 ^th of the Julian period, will be the 5507 ^th of the Jewish epoch or the epoch of the creation of the world.

This epoch is still in use among the Jews.

The epoch of the creation, in use among Greek historians, is the year 787 before the Julian period, corresponding to the year 5500 B.C.

Thus, adding 787 to a given year of the Julian period, the sum is the year of this epoch . For example, 6459 being the year we are in in the Julian period, the present year of this epoch or of the age of the world, following the Greek calculation, will be 7246.

The author of this epoch is Julius the African, [7] who got it from the historians. But when they tried to make use of it for civil purposes, eight years had to be added to it so that each year divided by fifteen could mark the indiction [8] which the eastern emperors used to date their charts and diplomas.

The epoch of the creation in use among the modern Greeks and the Russians is the year 753 before the Julian period, or the year 5509 B. C. beginning the first of September; however, the Russians later adopted the Julian calendar which begins the year on the first of January.

Thus, adding 795 to a given year of the Julian period, the sum will be the year of this epoch ; thus the Julian year today being 6468, the present year of the creation, according to this calculation, will be 7263; and subtracting 5508 from the present year 7263, the remainder will be the current year 1755.

This era was used by the eastern emperors in their diplomas, and that is also why it was called the civil year of the Greeks. It is indeed the same as the epoch of the Constantinopolitan period; that is why some call it the epoch of the period of Constantinople. See Period.

The Alexandrine epoch of the creation is the year 780 before the Julian period, which corresponds to the year 5494 B.C. and begins on the 29 ^th of August.

Thus, adding 5493 to the present year A.D. 1755, the sum 7248 will give the present year of this epoch , or the number of years passed since creation, following this calculation method.

This epoch was imagined by Panodorus of Alexandria, an Egyptian monk, to facilitate the calculation of the Passover; [9] that is why some writers call it the Greek ecclesiastical epoch .

The Eusebian epoch of the creation is the year 486 of the Julian period, which corresponds to the year 4228 B.C. and begins in the fall.

Thus, subtracting 486 from the present Julian year 6468, or adding 4228 to the present year of Christ, the number 5983 which results will be the present year, following the Eusebian epoch .

This epoch is the one followed in the chronicle of Eusebius and in Roman martyrology.

The epoch of olympiads is the year 3938 of the Julian period, corresponding to the year 776 B.C. and to the year 2985 of the creation; it begins at the full moon after the summer solstice, and each olympiad contains four years.

This epoch is very famous in ancient history; it was in use principally among the Greeks, and drew its origin from the Olympic games which were celebrated at the beginning of each fifth year. See Olympiad.

Epoch of the foundation of Rome , or Urbis conditæ , V.C. , [10] is the year 3961 of the Julian period, according to Varro, or the year 3962 according to the capitoline fasti ; it corresponds to the year 753 or 752 B.C. and begins on the 21 ^st of April. Therefore, if the years of this epoch are fewer than 754, they must be subtracted from 754 or 753 to have the corresponding years B.C. If they are larger than 754, they must be added to get the year of the foundation of Rome, and 754 subtracted from them to get the year A.D.; thus, using Varro’s calculation, the present year 1755 is the 2518 ^th of the foundation of Rome.

The epoch of Nabonassar is the year 3967 of the Julian period, which corresponds to the year 747 B.C. and begins on the 26 ^th of February.

This era is so called from the name of its institutor Nabonassar, king of Babylon, and is the one which Ptolemy used in astronomical observations, as well as Censorinus and several others.

The Diocletian epoch , or epoch of martyrs, is the year 4997 of the Julian period, corresponding to the year 293 A.D. It is called the era of martyrs because of the great number of Christians who suffered martyrdom under the reign of that emperor.

The Abyssinians, who still use it in all their computations, call it the years of grace , although their years do not form a continuous succession since that epoch; but when the Dionysian period of 534 expired, they begin counting again beginning with 1, 2, etc.

The epoch of the Hegira , or mohammedan epoch , is the year 5335 of the Julian period, which corresponds to the year 622 A.D. It begins on the 16 ^th of July, which is the day Mohammed fled from Mecca to Medina.

This epoch is the one the Turks and Arabs, and in general all the Muslims and followers of Mohammed, use. Its first institutor was Omar, the third emperor of the Turks. The astronomers Alfraganus, Albategnius, Alfonso, and Ulugh Beg place the flight of Mohammed at the 15 ^th of July, [11] but all the peoples who make use of this epoch set it at the 16 ^th of the same month. See Hegira.

The epoch of the Seleucids , which the Macedonians use, is the year 4402 of the Julian period, corresponding to the year 312 B.C. See Seleucids.

The Persian or yezdegerdian epoch , is the year 5345 of the Julian period, corresponding to the year 632 A.D. and beginning on the 16 ^th of June.

This epoch is set at the death of Yezdegerde, last king of Persia, killed in a battle against the Saracens.

The Julian epoch , or epoch of the Julian years , is the year 4668 of the Julian period, corresponding to the year 45 B.C.

This epoch begins in the year Julius Caesar reformed the calendar. That year is called the year of confusion . See Year.

Gregorian epoch . See Gregorian.

The Spanish epoch is the year 4676 of the Julian period, corresponding to the year 38 B.C. See Era.

The Actiac or Actian epoch is the year 4684 of the Julian period, corresponding to the year 30 B.C. and beginning on the 29 ^th of August.

The other memorable epochs are those of the flood, year 1656 of the creation; the birth of Abraham in 2079; the exodus of the Israelites or their exit from Egypt in 2544; the construction of the temple of Jerusalem in 3002; the destruction of that same temple in 50 A.D.; the capture of Constantinople by the Turks in 1453, etc. Chambers . [12]

1. Jacques Bénigne Bossuet (1627–1704), bishop of Meaux, Discours sur l’histoire universelle (1681). This allusion is more a signal of good behavior than anything else, since d’Alembert knows very well that practically the only document pertinent to Bossuet’s notion of history is the Hebrew Bible.

2. Louis IX and Charles V.

3. D’Alembert’s contribution to this article ends here; the rest is by Mallet.

4. Denis Pétau (1585–1652), a prolific Jesuit theologian, published Opus de doctrina temporum in 1627.

5. Doctrine des temps was, as just seen above, the expression Pétau used in his title.

6. Term invented to contrast with Livy’s title Ab urbe condita for the history of Rome, urbs being the city and orbis the world.

7. Sextus Julius Africanus, early 3 ^rd century, from the first volume of his Chronographiai , a history of the world.

8. A period of fifteen years; see the article Indiction.

9. La Pâque : Passover or Easter, depending on the focus of the discussion.

10. V.C. is simply the abbreviation for urbis conditæ , since Latin did not distinguish between U and V .

11. The Arab astronomers are: Al-Farghani (known as Alfraganus in the West; 800/805-870); Al-Battani (known as Albategnius in the West; c. 858-929); Alfonso X of Castille (1221-1284); and Ulugh Beg (1394-1449).

12. The reference is to Chamber’s Cyclopædia (1728), which is the source of this list, vol. I at the word “Epocha.”