Saturday, April 20, 2013

Let's play the tricky game
about the correctness
of eras, epochs, and calendars /

Ας παίξουμε το πονηρούτσικο παιχνίδι
περί ορθότητας
των χρονολογικών περιόδων,
των εποχών και των ημερολογίων





b.c.e. / c.e.
π.κ.χ. / κ.χ.

Eras
The term ‘era’, for a chronology in which years are numbered continuously from a starting point or epoch without reverting to 1, is derived from the post-classical Latin word aera or era, properly denoting the place of an item in a numbered sequence and hence used for the serial number of the year (now called by the French term millésime). The chronological use originated in Spain, where years expressed in the local dating-system (for which see below) were indicated not by anno but by (a)era (e.g. era mclxxiii, as it were ‘no. 1173’ = ad 1135); the word was extended to mean the dating sequence itself, and then others like it. The great merits of era datings are that the intervals between events are easily calculated without the need to add up the lengths of reigns or count off magistrates from a list, and that future years may be identified as far ahead as one wishes.

The epoch of an era may be a correctly dated historical event, such as the Prophet Muhammad’s hijra or departure from Mecca to Medina, from which the Muslim era is reckoned (see Chapter 6); but for chronological purposes it makes no difference if the date is wrong or doubtful, as in the case of the Christian era, nor if the event itself is legendary, like the accession of the Emperor Jinmu in 660 bc, from which in the ultra-nationalist period Japanese years were counted.

Eras may be reckoned either in current years, in which year 1 begins immediately after the epoch, or in elapsed years, in which it begins only when a year has already been completed. Both systems are familiar to us for stating ages: when we say that a person is in his or her 25th year we are counting current years, but when we say that the same person is 24 years old we are counting elapsed years. In era dating current years are the norm except in India; of the many Indian eras the most important is the Saka era, reckoned in elapsed years from ad 78, on which the National Calendar is based (see Chapter 6).

In Hellenistic and Roman times there were numerous local eras, commemorating political events, but few were of any significance outside the city or province concerned. These eras do not include the ab urbe condita reckoning from 753 bc familiar in modern writings about Rome, since Romans were not agreed on the correct date of foundation; when an event is said to have taken place so many years after the foundation, this is no more a formal dating than ‘a hundred years after the Norman Conquest’ would be in English.

The most important era in classical antiquity was the Seleucid era of western Asia. In 311 bc the Macedonian satrap or governor of Babylon, Seleucus, having restored himself to power by force of arms, began numbering his years of renewed office from 1 Nisanu, in that year corresponding to 3 April; when a few years later he took the title of king, he did not alter the count. His Macedonian and other Greek subjects adopted it, but, being used to Macedonian years that began in the autumn, they placed the epoch six months earlier, in late 312 instead of early 311. After his death – by which time his realm extended from Turkey to Tajikistan – the count was maintained by his successors; it remained in use throughout antiquity, was kept up by Jews (who called it ‘the reckoning of contracts’) till the Renaissance (even longer in Yemen), and survived amongst Nestorian Christians till the second half of the 20th century, when, styling themselves the Assyrian Church of the East, they adopted an era with epoch 1 April 4750 bc, based on a surmised foundation date of Asshur.

Other eras, such as that of Provincia Arabia (epoch 22 March ad 106), were more localized and mostly short-lived; an exception in the latter respect is the Hispanic era, with epoch 1 January 38 bc. This is traditionally associated with Augustus, for no clear historical reason, but may commemorate the beginning of Roman conquest in the Pyrenaean region where the earliest (but contested) examples of this reckoning have been found. The era is indubitably attested from the late 4th century; it was used in Visigothic Spain (except for the easternmost portions, where it appears only after the Reconquista), and lasted in official use till the later Middle Ages: in Aragon till 1350, in Castile till 1383, and in Portugal till 1422.

World eras

The era that would ultimately displace the Seleucid era amongst Jews was a world era, that is one reckoned from the creation of the world; for this purpose they adopted the epoch already used for calendrical calculation, 3761 bc (see Chapter 6). The Jewish year from 16 September 2004 to 3 October 2005 is thus am 5763, often (especially in Hebrew) written ’763; am, standing for annus mundi, or ‘year of the world’, is the conventional qualification for a year in any world era, including those devised by Christians. The basis of such eras was the chronology of the Old Testament, which is far from simple and is also considerably shorter in the Hebrew text and St Jerome’s Latin version than in the Greek translation known as the Septuagint. World eras were mainly developed by Greekspeakers, beginning with Sextus Julius Africanus (c. 221), who placed the conception of Christ on 25 March and made it the first day of am 5501. This is commonly taken to be 2–1 bc (though not all his datings fit). Nearly a century later, Eusebius of Caesarea dated Creation to 5200 bc, Christ being born in am 5199; however,
he preferred to call this ‘year of Abraham 2015’.


Disseminated through Jerome’s translation of his Chronicle, Eusebius’ calculation became the standard theory in the West till Bede, using the Latin Bible, reduced the period between Creation and Nativity to 3952 years. Other Greek-speakers, however, preferred the higher interval of Africanus, or one close to it, but adjusted so that the Creation should take place on a Sunday; the most favoured was the era of Annianus (early 5th century), in which the Creation took place on Sunday, 29 Phamenoth = 25 March 5492 bc, and the Incarnation, meaning the Conception of Jesus Christ, on Monday, 29 Phamenoth am 5501 = 25 March ad 9.

However, although reckoning the year from the anniversary of Creation was theologically attractive, in practical life it was inconvenient; the epoch was therefore adjusted to the civil New Year before Creation, 1 Thoth/29 August 5493 bc. This caused Incarnation and Nativity to fall in different years: rather than redesignate the year of Nativity 5502, the Alexandrians reassigned the Incarnation to am 5500, which had the advantage of placing it on a Sunday, 25 March ad 8; the am 5501 in which the Nativity supposedly took place now began on 29 August ad 8. This became the first year in an era still used in Ethiopia, where the Year of Grace 2000 will begin on 30 August Old Style = 12 September 2007.

The 7th-century Chronicon Paschale (so called because it began with an account of Easter reckoning) opted for 25 March 5509 bc. Later Byzantines, however, preferred to defer the Creation till the beginning of the civil year on 1 September; an unsuccessful alternative was 25 March 5508. In Russia the year of Creation was the regular dating system, reckoned originally from 1 March 5508 (less often 5509) bc but by the later 14th century from 1 September 5509 bc, till by decree of Peter the Great 31 December am 7208 was followed by 1 January 1700 Old Style.

Perpetuated reigns
Some eras developed out of regnal years continued after the death of the monarch: as we saw in Chapter 6, the Zoroastrian era commemorates Shah Yäzdegird III, whose first regnal year began on 16 June ad 632. Several such eras were created by astronomers, who found continuous numeration helpful; one is the era of Nabonassar, reckoned in Egyptian anni vagi from 1 Thoth = 26 February 747 bc, the first year (on the Egyptian reckoning) of the Babylonian king from whose time onwards astronomical records were preserved. Another is the era of Diocletian.

When Augustus (as he later became) conquered Egypt in 30 bc, he ruled it as king through a viceroy or prefect, outside the general provincial system, counting his years on the established nonaccession system. His successors followed suit until Diocletian, at the end of the 3rd century ad, integrated Egypt into his reformed provincial structure and introduced consular dating. That was highly inconvenient for astronomers, who would need to keep lists of consuls in order to understand their own observation-records; instead, they continued to count by Diocletian’s regnal years, of which the first was 284/5, even after his abdication in 305. This was the method used to designate years in Alexandrian Easter tables; it spread to general dating purposes, and is still the favoured era of the Coptic church. However, since Diocletian, in his last years of power, had unleashed the Great Persecution against the Church, from the 7th century the era was renamed that of the Martyrs. After year 532 of the Martyrs (= ad 815/16) years are sometimes numbered over again in Paschal cycles of 532 years, so that (for instance) year 257 may be not 540/1 but 1072/3 or 1604/5.

Christian era
The odiousness of the persecutor’s name was also the reason given by Dionysius Exiguus for replacing, in his Easter table, the era of Diocletian with that of the Incarnation, ‘so that the beginning of our hope might be better known to us and the cause of human restoration, that is the passion of our Redeemer, might shine forth more clearly’. The Incarnation is not the Passion; but Dionysius was brushing aside his predecessor Victorius, who had designated the years in his table by an era of the Passion reckoned from ad 28, his compatriot Prosper’s inaccurate date for the two Gemini. (This was not the only Passion era known: at Rome in Bede’s day years were counted from ad 34, or perhaps 33; other dates are found in the East.)

Dionysius treats his Incarnation date as unproblematic and uncontroversial, neither explaining how it is known nor claiming it as his own discovery. Since most earlier writers had dated the Incarnation to 2 bc, this has been difficult to explain: one theory requires him to misread or misrepresent the Olympiad date of Diocletian’s accession in Eusebius’ Chronicle, compiled in the late 3rd century, or its translation by Jerome; however, since the Nativity in ad 1 is already found in a calendar written in 354, another scholar shifts the blame to Eusebius, supposing a miscalculation in the Easter table that we know him to have written.

Another suggestion is that Dionysius deliberately fudged his figures in order that leap years should continue to be divisible by 4, as in the Alexandrian tables; for although the leap day had been added in the previous year, it was in the exact multiples, such as year 244 of Diocletian, that it affected the Easter calculations. It was and is convenient that year 248 of Diocletian should be 532 of the Incarnation, rather than 531 or 533. The Church historian Socrates, translating into Greek the report that the emperor Valens began his reign on V Kal. Mart., rendered it in the normal way as 25 February without realizing that the year in question was a leap year, so that the correct date was the 26th. Had he, like us, known the year as 364, he could have seen the fact at once.

Nevertheless, Dionysius’ date shares with the 2 bc it displaced the defect of being incompatible with both Gospel narratives, for St Matthew’s story of the Magi and the Holy Innocents requires the Nativity to have taken place at least two years before the death of Herod the Great at Passover 4 bc, and St Luke’s narrative places it in ad 6, when ‘Cyrenius’, that is to say P. Sulpicius Quirinius, was incorporating Judaea into the Roman province of Syria. No solution of the problem has yet satisfied either believers or non-believers in the literal truth of the Bible.

The year of the Incarnation
When preachers say on Christmas Day that Christ was born so many years ago, they always give the number of the current year, implying that the Nativity took place on 25 December 1 bc; that was also the view of those churches and orders that counted the era from that date (see below). By contrast, although this is the first year in Dionysius’ 19-year cycle, Bede, following Irish sources, took him to have put the Incarnation in a year whose characteristics match the second year of his cycle, ad 1; this is more compatible with the preference for current over elapsed years, though the computist of 243 had devised an elapsed-year era of the Exodus. Dionysius himself is unlikely to have given the matter any thought.

The spread of AD dating
Dionysius’ Incarnation era, like Victorius’ Passion era, was originally devised for the sake of Easter tables; a few authors use it for relative chronology, typically in conjunction with the incompatible chronology of Eusebius. However, the habit of writing
annals, or brief records of a year’s events, in the blank spaces of Easter tables encouraged a closer association between era-date and year; this was particularly congenial to Irish and English monks, for whom the Emperor was a foreign potentate and whose countries were divided among numerous kings and kinglets.

Although the prevalent means of identifying the year in Ireland, at least in monastic writings, was by the feria and lune of 1 January, we find explicit dating by Victorius’ Passion era as early as 658. In Northumbria by the late 7th century Dionysius’ Easter reckoning prevailed over Victorius’; it was therefore Dionysius’ era that Willibrord, the apostle of the Frisians, employed when he noted in his calendar that he had crossed the sea to Francia ‘in the 690th year from Christ’s Incarnation’, had been ordained bishop in 695, and was now living in 728.

The decisive moment, however, was Bede’s decision to use this reckoning in his Ecclesiastical History of the English People, rather than the world era of his chronicle; the History, an instant classic, brought Incarnation dating to the attention of Continental readers, who in due course began to adopt it for themselves. Although alternative epochs of 22 bc (Abbo of Fleury in the 10th century) and 23 bc (Marianus Scottus of Fulda in the 11th) were proposed in order to salvage the Western tradition that the Crucifixion took place on 25 March, which was luna XIV in ad 12, and Gerlandus of Lotharingia in the 11th century adapted the Alexandrian Incarnation era to the Julian calendar by subtracting seven years from the date ad, the Dionysian era prevailed, ousting even the deep-rooted Hispanic era, to become the world-wide standard even outside Christendom.

Dating ‘before Christ’
The Christian era is the only era in which dates before the epoch are regularly identified as such; if occasional instances in the Middle Ages are still comparable with casual references to events so many years before the foundation of Rome or the Hispanic era, since the 18th century it has been normal to count ‘years before Christ’ on the same footing as ‘years of our Lord’. The main resistance came from German historians of ancient Rome, who preferred to canonize the ‘Varronian’ date for the city’s foundation, and switch to the Christian era only from the epoch onwards, so that 753 was followed by 1; this usage is now obsolete.

Astronomical dating
Whereas in normal usage ad 1 is preceded by 1 bc, in astronomical reckoning the year 1 (unlabelled) is preceded by year 0, and that in turn by −1, corresponding to 2 bc; correspondingly 45 bc is −44, 100 bc is −99, and so on. This not only assists calculation (from −7 to 3 is 3 − (−7) years = 3 + 7 years = 10 years), but makes all years divisible by 4 leap years; in the normal reckoning this applies only to years ad, those bc being leap if of the form 4n + 1.

Ideological content of eras
Although a regnal year may send a message at a time of political contention, it is eras that are the most obviously ideological form of chronology. To the many examples already seen may be added the turmoil caused in Iran when on 24 Esfänd 1354 solar Hejri (the Farsi pronunciation of hijrı¯), corresponding to 14 March 1976, Mohammad Reza Shah decreed a new Shahänshahi (‘Imperial’) era, reckoned from Cyrus the Great’s accession to the Persian throne in 559 bc, to begin a week later (1354 being a leap year) at Nawruz 2535.

This, one of many attempts at associating the dynasty with the glorious Achaemenids of ancient times, was received by the people as an affront to Islam. A Western reader may conceive some faint idea of the indignation aroused by imagining that Mussolini, instead of instituting a Fascist Era with epoch 29 October 1922 to be used concurrently with the Christian, had replaced the Christian era with that of Rome, so that 1923 had become 2676. Popular protest forced restoration of the Hejri era from 5 Shährivar 1357 (27 August 1978).

The Christian era is too well established to be challenged for its religious origin; in China indeed, where Christianity has never been more than a minority religion, it was made official by the antireligious Communists. However, the name has come under attack; whereas Muslims freely speak of the mı¯la¯dı¯ or ‘Nativity’ year, Continental secularists prefer to call the era simply ‘ours’ (notre ère, unsere Zeit), and amongst English-speakers the term ‘Common Era’, already standard in Jewish usage (compare Hebrew ha-sefirah, ‘the count’), has become widespread in American academic writing. Even some Christians have accepted it, whether in an anti-proselytizing spirit or because there are no grounds for believing the era’s epoch to be the true date of the event that it commemorates. Nevertheless, if it does not commemorate the birth of Christ, it has no business to exist at all, for no other event of world-historical significance took place in either 1 bc or ad 1.

Beginning of the year
If Incarnation and Nativity are to fall in the same year, it must begin no later than 25 March; but this date is impossible for a computistic year, since Easter may precede it. Yet Dionysius’ lunar regulars presuppose a year beginning in September as at Byzantium (it was Bede who recalculated them from January); if forced to specify, he might have stated that his epochal year ran from 1 September to 31 August, incorporating the Incarnation, from which he counts, but not the Nativity, from which he does not.

His Western readers, however, took some time to recognize the difference between Incarnation and Nativity. It was quite frequent for years to be reckoned, not from 1 January ad 1 – a date disliked by the Church on account of the pagan festivities it had failed to suppress – but from seven days previously, 25 December 1 bc, the supposed date of the Nativity. This, despite Bede, was the practice in Anglo-Saxon England, and long remained in use in Benedictine monasteries; but it was ultimately supplanted by the rival principle of counting from the Incarnation proper on 25 March, the Annunciation or Lady Day. In the late 10th century, we find in parts of southern France and northern Italy an epoch of 25 March 1 bc, resulting in a millésime 1 higher than in the modern reckoning till 31 December; this fell out of favour except in Pisa, for which reason it is known as the calculus Pisanus. More widespread was Annunciation in ad 1, with a millésime 1 lower than the modern between 1 January and 24 March; this was characteristic of Florence and England, for which reason it is known as the stilus Florentinus, or the ‘custom of the English church’ (consuetudo ecclesiae Anglicanae).

Pisa and Florence retained their respective usages down to 1749, before being ordered to count from 1 January by Grand Duke Leopold of Tuscany; the English style was reformed by Act of Parliament in 1751 (Scotland had used 1 January since 1600). Venice preferred to count from the beginning of the Incarnation month, that is 1 March ad 1, and continued to do so in official documents till the suppression of the Republic in 1797. If this mos Venetus was more convenient than changing the millésime within a month, the French custom, mos Gallicus, of beginning the year at Easter was less so: but even after the royal ordinance abolishing it in 1564 local resistance prolonged its use in some parts of the country (in the Beauvaisis till 1580).

Exact study of documents has shown that the medieval dates for the change of millésime varied within as well as between countries to an even greater extent than is stated in reference books. Nevertheless, throughout Europe west of the Byzantine Empire, ‘New Year’ and its equivalents in other languages regularly meant 1 January even before the adoption of the Modern Style, as counting from that day is known.

Hybrid systems
Some Christian chronologies state the years of their eras according to the 532-year Paschal cycle: in Georgia from the 9th to the 19th century, dates were given in years of the kronik’oni, a Paschal cycle reckoned from ad 781 or 1313, respectively the 13th or 14th from Creation in 5604 bc. Coptic years of the Martyrs may also be reduced to years of a Paschal cycle (see p. 122).

* Leofranc Holford-Strevens,
The History of Time: A Very Short Introduction,
Oxford University Press 2005,
pp./σσ. 118-128.



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