The Second Round of Debates on the Timing of Easter
How Exactly Do You Determine the Date of the Pascha/Easter?
(avg. read time: 18–36 mins.)
The debate around determining the proper date of the Pascha/Easter proved much more wide-ranging and intransigent than the previous one about its relation to Passover/Pesach. Indeed, it would lead to the calendrical reform that now divides the East and West. But we will get to that later. For now, it is important to examine what drove the different methods for calculating the date of Pascha in the first place. As the majority celebration in the Roman world at large by the third century was to observe Pascha on a Sunday, this question remained: which Sunday? The most obvious answer to stay consistent with the logic that led to the Sunday observance in the first place is to observe it on the Sunday after Passover. But how do you determine the date of the Passover? It is the fourteenth day of the first month according to the lunar calendar, but how do you figure out when that month begins and when the fourteenth day has arrived?1 Do you copy the rabbis’ homework, or do you adopt a different method? Even some Christians who observed the Paschal Sunday followed the former approach (e.g., Did. apost. 21), but the majority who left behind a record of their thought followed the latter approach and this decision led to a variety of different methods for calculating the date of Easter.
But given the historical reasons for connecting the Pascha to the Passover, why diverge from the Jewish calendar in the first place? One rather obvious reason is the basic desire to dissociate from Jews that accompanied the “parting of the ways.” We have already noticed this in Epiphanius’s Panarion (50.1–2), but this desire is also clearly expressed in a letter of Constantine following the First Council of Nicea in 325, which has been preserved in Eusebius, Life of Constantine 3.18–20; Theodoret, Church History 1.9; and Socrates Scholasticus, Church History 1.9. One of the chief reasons he cites for not taking calendrical cues from Jewish reckoning was their great sin in killing the Lord Jesus. This kind of statement was frequently made among early Christians and the anti-Judaism of the early church has been so frequently documented in works of the post-Holocaust era that we need not expound on it here. But it is important to recognize that this sentiment played a role in early Christian deliberations on when to celebrate Easter. It was, however, not the only factor.
A second reason concerned the imprecision and variability of Jewish calendars at the time. Jews had local variations and different ways of determining the proper time of the Passover, apart from the standardized rabbinic model and the nineteen-year cycle utilized today.2 Aristobulus of Alexandria was thought to have observed the “rule of the equinox,” in which Passover always fell after the vernal equinox, and this rule would be influential even in later Christian texts, as we will see below.3 Later Jews in Alexandria had their own independent means of designating a date for Passover through astronomy, of which Alexandria was a bastion.4 Antiochene Jews (or likely Antiochene) had their own timetable mentioned in a document drafted by Eastern bishops in the event of the contentious Council of Sardica (343). The bishops had drafted a list of thirty dates for the Paschal full moon from 328–357, but it also produced an accompanying list of dates for the Jewish Passover from 328–343 (as, apparently, they did not wish to attempt to predict the dates when Jews would observe it in the future), wherein the dates range from March 2 to March 30.5 Thus, they seem to have observed a “rule of March,” in which Passover was always observed in the Julian March.6 Furthermore, Josephus writes of a letter announcing the death of Tiberius (March 16, 37 CE) coming during a feast, which likely would have arrived in Judea in late April (Ant. 18.122–124).
The rabbis themselves lacked a precise calendar until sometime in the fourth century. As noted previously, the lunar calendar needed an intercalated thirteenth month every so often to be aligned with the solar calendar, but the rabbis initially decided on whether or not to intercalate by paying attention to three signs, any one of which could be used as a reason to intercalate a month: the premature state of crops, the undeveloped state of fruit, and the lateness of the equinox (t. Sanh. 2.2–3). What qualifies as the “lateness of the equinox”? It must be sixteen days or more later in the month (2.7). The Tosefta further indicates that the month could not properly be intercalated if the pigeons or lambs born in spring were unseasonably late, but that rabbis could still use this reasoning as a basis for their decision (2.4). Intercalations had to be done with a full, proper month and could not be done a year in advance (2.8). In fact, decisions were typically made in Adar, the month before Nisan (2.13), although it was technically allowed any time after Rosh Hashanah and before Nisan, and thus at any point in the last six months of the year (2.7; b. Roš Haš. 7a; b. Sanh. 12a). The Tosefta also expounded on a certain set of instructions in t. Sanh. 2.12 by saying that the month could be intercalated due to difficulties of travel (e.g., roads and bridges being damaged), ovens being unfit for roasting the Passover offering, or Diaspora Jews on the road who need more time to get to Jerusalem (but not in the case that they have not left their houses; b. Sanh. 11a). In both sources, the presumption was that decisions on intercalations came from Judea (t. Sanh. 2.13; b. Sanh. 11b).7 Such imprecise calculations, local variations, and logistical problems (especially as the Easter/Paschal season expanded and the Lenten season developed, making more obligations on people’s schedules) were not conducive to what would ultimately become the goal of consolidating traditions and trying to get everyone on the same page of celebrating Pascha as one Church.
With all of these factors of variability, unpredictability, and imprecision, one particular consequence became a third reason cited for parting with Jewish reckoning of the Passover: the Jews would face the prospect of celebrating the Passover twice in a year, which seemed absurd to the early Christians.8 Indeed, both the fact that the Jews would sometimes celebrate Passover before the equinox (Anatolius, Paschal Canon [Latin] 8–9; cf. Peter of Alexandria, fragments on Passover 1–2, 6–7 [ANF 6:281–83]) and that they could celebrate an annual Passover twice in one year (Eusebius, Vit. Const. 3.18; Epiphanius, Pan. 3.70.11.5–6) were popular points of criticism. How did such a thing happen? Beckwith has a convincing explanation rooted in the logistics of travel in the ancient world. As we know that there were local variations of Jewish calendars, that decisions on intercalations came from Judea and Eretz Israel, and that letters were sent out to convey these decisions (per m. Roš Haš. 1.3–4; t. Sanh. 2.6; y. Meg 1), what likely happened was that cities more distant from Judea (such as Rome and Carthage) observed Passover according to their own calendars, but they did not receive the news of the intercalation from Judea until later, at which point they would observe Passover again.9 Even if the decision to intercalate was made early in the second half of the year,
the safe reason [sic.] for sailing ended only ten days into the second half of the year (Acts 27:9), and less than two months later sailing became impossible, remaining so until just before the beginning of Nisan. Consequently, an earlier decision would not be likely to make much difference. These difficulties probably led the Jews of Rome and Carthage to celebrate the Passover at the approximate date when it would have fallen without the intercalary month, and then, if they subsequently learned that Second Adar had been added, to celebrate it again a month later.10
For these reasons, many of the early Christians found it undesirable to rely on Jewish calendars and thus went so far as to say that the Jews did not observe the proper Paschal full moon.
The Christians were thus tasked with finding a calendar that would both accurately follow the vernal equinox (and thus, at least indirectly, the tropical solar year) and accurately follow the first fourteenth moon on or after the equinox (and thus the lunar year made of synodic lunar months, which track the phases of the moon). They needed to be able to track a lunar date on a solar calendar. Such methods would also require determining epacts, the “age” of the moon at a given time, since they would need to know what date the fourteenth moon of the lunar month fell on and how soon afterwards the next Sunday fell.
The basic problem that created the multiplicity of methods is the fact that there are not an even number of lunar months in a solar year. Some years have twelve new moons while others have thirteen (so-called “embolismic” years), precisely because of the differences in lunar and solar years.11 Furthermore, synodic lunar months, on which the lunar calendar is based, are not an even number of days. They are actually 29.5306 days, which were typically expressed in ancient and medieval texts alternately by 29 (“hollow” lunar months) or 30 days (“full” lunar months). Conversely, the mean tropical solar year, the time it takes for the Sun (seen from the perspective of Earth) to return to its position in the cycle of seasons (from vernal equinox to vernal equinox, from summer solstice to summer solstice, and so on), is 365.2422 days. If you divide 365.2422/29.5306, you get 12.3683 as the number of synodic lunar months in a tropical solar year. If you substitute the Julian reckoning of the year as 365.25 days and you divide by 29.5306, the result is 12.3685.
To provide an orderly system for computing a lunar date on a solar calendar, it is thus necessary to eliminate the remainder and find a number of solar years that contains a whole number of lunar months (or, as the ancient and medieval writers preferred to call them, “lunations”). This is where we get the Easter/Paschal cycles from. Different systems of cycles expressed the remainder of months (.3683 or .3685) by rounding it to a number of different fractions: 3/8 (.3750), 7/19 (.3684), and 31/84 (.3690). What do these fractions mean in practical terms? An eight-year cycle would compensate for the remainder by including three embolismic years (i.e., years with thirteen new moons) for a total of ninety-nine lunar months over the course of eight years. A nineteen-year cycle would compensate for the remainder by including seven embolismic years for a total of 235 lunar months over the course of nineteen years. And an eighty-four-year cycle would compensate for the remainder by including thirty-one embolismic years for a total of 1,039 lunar months over the course of eighty-four years. These cycles could also be multiplied to provide even more long-term guidance for churches, as the eight-year system could be presented in a 112-year cycle and the nineteen-year system could be presented in a ninety-five-year or 532-year cycle.12 Two of the methods were already in use among scholars of the time. The nineteen-year cycle was based on the Metonic cycle developed by Meton of Athens (fifth century BCE). Julius Africanus uses both the eight-year cycle and the nineteen-year cycle, both of which he says are in use at the time, to apply the seventy weeks of Dan 9 to the time between Nehemiah and Jesus (Chronographiae F93, 281, 283, 285).13 The eighty-four-year cycle seems to have been a Christian invention.14
One more complication to these formulae was the fact that the whole number of lunar months did not necessarily amount to every day being charted precisely. There were also days known as the saltus lunae, lunar leap days that would deduct a day from the epact. They would be done on however frequent a basis was necessary to bring the lunar and solar calendars back into alignment and each of these cycles had different times for the saltus.
With these considerations in mind, Christians in the third century began developing methods of calculating the date of the Paschal full moon and thus of the subsequent Sunday years in advance. The earliest example comes from “Hippolytus.” I put the name in quotes because the authorship of works attributed to Hippolytus is highly debatable, especially when one asks, “which Hippolytus?” The Hippolytus traditionally picked is one Hippolytus of Rome (170–235), but for the sake of simplicity, to avoid any unnecessary claims, and in recognition that the third-century date would remain the case whether this is referring to Hippolytus of Rome or not, I will simply refer to the author as “Hippolytus.”15
I have mentioned in an essay I wrote about Christmas that Hippolytus had developed a Canon paschalis, a lunar calendar written in 222 on a statue found in Rome that was supposed to track the date of Passovers by tracking the date of the fourteenth moon of the month of Nisan.16 What I did not mention in that case was that this calendar was for the purpose of calculating the date of the Christian Pascha. His cycle is technically a double eight-year cycle repeated seven times over the course of 112 years.17 It seems to incorporate the saltus into years 3 and 11, which were also solar leap years on the Julian calendar (224, 232, and so on) and it seems to restrict Pascha celebration to the sixteenth through twenty-second moons of the Passover’s lunar month. However, due to certain calculations, an assumption that the world was created on March 25 (an assumption confirmed to exist in the next text and which correlates with the date to which he assigns Jesus’s death in 29 CE), and an assumption that the first appearance of the full moon was on March 29 (based on a certain popular reading of Genesis 1), the Canon indicates that Hippolytus would ultimately allow for Pascha to be celebrated between March 20 and April 21. The latter date would remain an established limit in Roman tradition, but the former date was before either the eventual Alexandrian reckoning of the equinox (March 21) or the Roman one (March 25, just as the winter solstice was December 25) and thus would be accepted by no one. Furthermore, the predictions of this canon were wrong three years after it started. When Hippolytus realized his errors, which were then literally written in stone, his later chronicling work would rely on calculating years rather than days or moon phases.
Our next text is likely a critique of Hippolytus, among others, from a North African author dubbed “Pseudo-Cyprian” in his On Computing the Paschal Feast (243).18 Like Hippolytus, this author begins his calculations with the assumption that the world was created on March 25 and that the first appearance of the moon was a full moon on March 28 (4, 6). But his proper calculation of Pascha dates begins with the exodus and the patterns in his calculations, along with his use of Daniel’s seventy weeks that corresponds to Africanus’s method, indicate that he is also using a double eight-year cycle repeated over the course of 112 years with corrections to Hippolytus (9–19).19 His basic method for calculating the Passover moon from year to year rests on the assumption that Passover moon could appear between March 15 and April 13 and that these limits could thus dictate when to subtract eleven days from the previous year (to account for the difference in the lunar and solar years) and when to add nineteen days if the subtraction went beyond March 15 (6–7; this method may have also been used in the calendar of the Antiochene Jews who observed the “rule of March” noted above). In the year of his writing, 243, he assigns the date of the Passover moon to March 21 (a Tuesday) and the date of the Pascha to the Sunday of March 26.
Later in Alexandria, the bishop Dionysius (d. 264/5) would produce his own paschal canon of an eight-year cycle. In his Festal Epistles, he was the first Christian on record to articulate the rule of the equinox, that the Pascha should only be observed after the vernal equinox (Eusebius, Hist. eccl. 7.20). However, these epistles and his cycle have not been preserved. Afterwards, it seems that support for the eight-year cycle fizzled out as its predictive power for the Paschal full moon, and thus the proper subsequent Pascha date, proved to be too unreliable.20
This leads to one of the most influential figures in the field of Paschal computation: Anatolius of Laodicea (d. 283). He was the first to develop a nineteen-year cycle, based on the Metonic cycle mentioned above, for the purpose of determining the date of Pascha. His account of his reasoning has been partially preserved in Eusebius’s Church History (7.32.13–19), but there is also a longer Latin version, Liber Anatolii de ratione Paschae (translated here). While the Latin text does include the text from Eusebius, the extent to which the rest of the text goes back to Anatolius is disputed.21 To avoid the complexities of textual analysis here, I simply say that the remaining Latin text contains a mix of theological justifications that can be found elsewhere and arguments that seem to be more relevant as a response to later computations, such as we will see from Victorius of Aquitaine, and in allowable ranges of the Easter moon (i.e., how long after the Paschal full moon can the Christian Pascha be observed?). Indeed, Anatolius was a well-respected authority in this field who was cited centuries after his death.
Anatolius began his cycle with a new moon on the 26th of the Egyptian month of Phamenoth, which corresponds to March 22, and which would place the Paschal full moon at April 5. He then cites Jewish sources—including Philo, Josephus, Musaeus (otherwise unknown), the Agathobuli (otherwise unknown), and Aristobulus (whose work is extant only in fragments)—to justify this decision by noting when they regarded the proper celebration of the Passover to be. As Alden Mosshammer argues, Anatolius has likely misunderstood at least some of his sources, “What Anatolius attributes to Aristobulus requires only what Josephus says [Ant 3.248]—that the sun should be in the sign of Aries. Philo’s statement requires that the equinox should be within the month of Nisan, but not that the 14th day of the month must follow the equinox.”22 But the rule he derives from them is that the Passover offerings should be made after the vernal equinox, while the sun is in Aries. Whenever the sun is in this position, the Paschal full moon should be in the opposite position, the segment of the autumnal equinox (Libra). Eusebius’s text does not reproduce his cycle and the Latin version is likely corrupt.23 However, those who had his full document and his original Paschal cycle made it a popular tool, especially in Anatolius’s native Alexandria, where the nineteen-year cycle would be predominant.
Some decades later, after Constantine made Christianity a legal religion, bishops made attempts to consolidate Christian tradition and determine one common date for the celebration of Pascha. In 314, Constantine summoned the Synod of Arles to address the Donatist controversy addressed the previous year at a council in Rome. But as with other synods and councils, a number of canons were decreed by this group of bishops. The first canon decreed that Christians throughout the world should celebrate Pascha on the same day, although they made no ruling on what day that should be.24
Likewise, the famous First Council of Nicea (325) addressed this issue along with its main focus of the Arian controversy, but, contrary to popular claims, they issued no canons about it.25 The decisions of the council were instead relayed by Constantine in a letter he sent out across the Empire (which I have referenced above). Constantine states the council’s collective resolution that the feast should be observed on the same day throughout the world, although again this letter does not say when that day should be. The only guidance it gave was that Pascha should be separate from the celebration of the Jews (for reasons already noted) and that the church as a whole should be in agreement with the practice in Rome, Africa, Italy, Egypt, Spain, Gaul, Britain, Libya, Greece, Asia, Pontus, and Cilicia. Subsequent readers interpreted this guidance as meaning that the Church as a whole should observe the practice of celebrating Pascha on the first Sunday following the Paschal full moon (which, bear in mind, is not the same as the Passover according to contemporary Jewish reckoning) that falls on or after the vernal equinox (e.g., Epiphanius, Pan. 3.70.11; Apost. Const. 5.17), presumably because this was the majority practice at the time of the First Council of Nicea. Later instructions enforced this ruling, such as the first canon of the Council of Antioch (possibly 327), which stated that a bishop, priest, or deacon who observed Pascha at the same time as Passover would be excommunicated (cf. Apost. Const. 8.47.8, which elaborates by saying that the Pascha should not be observed “before the equinox”).
At this point, it is also necessary to correct a common misconception that many others have corrected. This ruling does not mean that the Nicene resolution dictated that Pascha must never coincide with or precede the first day of Passover (otherwise known as the Zonaras Proviso, after the twelfth-century commentator Joannes Zonaras). All that Constantine said to that effect is that:
it seemed very unworthy for us to keep this most sacred feast following the custom of the Jews, a people who have soiled their hands in a most terrible outrage, and have thus polluted their souls, and are now deservedly blind. Since we have cast aside their way of calculating the date of the festival, we can ensure that future generations can celebrate this observance at the more accurate time which we have kept from the first day of the passion until the present time.
In other words, the Christians were not to take their cues from Jewish chronology one way or the other. Given the imprecisions of the Jewish calendars noted above, it is entirely possible that Christians in various locales celebrated Pascha before the Jews celebrated Passover or before they celebrated a second time. Furthermore, one must remember that actual rabbinic practice in celebrating Passover was to celebrate it on the fifteenth day of Nisan (based on the fact that the Exod 12 directive says “on the fourteenth day at evening” [12:18], which the rabbis thought meant that it was actually the fifteenth day, since they reckoned days from sundown to sundown).26 While both Christians and Jews used multiple methods for calculating their feast dates post-Nicea, it is entirely possible that Pascha somewhere was celebrated before or during Passover somewhere else. In fact, if one follows the prevailing Dionysian method of calculation based on the Julian calendar and the prevailing rabbinic method based on astronomy, the 15th of Nisan may well have preceded or coincided with Pascha as many as thirty-one times (although all of these instances happened hundreds of years before Zonaras).27 In any case, one of the points of the ruling was to dissociate from the Jewish calendars altogether, not to reverse the earlier practice of the Church by using them as a guide of when it was not proper to celebrate.
However, the achievement of the goal of Arles and Nicea of getting the Church across the world to observe Pascha on the same day was significantly delayed (at least, to what degree it was ever achieved). Most notably, the centers of Rome and Alexandria disagreed on how exactly to determine the proper Sunday after the first post-equinox full moon, even if they agreed that such a time was the proper time to observe the Pascha. The Alexandrians had officially adopted the nineteen-year cycle by this point and the bishop annually sent out letters to notify other churches about the date of Pascha. The Romans used their own cycle (typically, an eighty-four-year one) and had their own established range of dates when they could observe Pascha: March 25 to April 21.
Later texts would claim that the First Council of Nicea dictated that Alexandria would have the responsibility of determining the most accurate date of Pascha and disseminating that information to the rest of the Christian world (e.g., Pseudo-Cyril Preface 4), which the Council never actually enforced. However, such a claim buttressed the de facto role of Alexandria in this time and the work its bishops did in conveying the dates to the rest of the world. Athanasius (296–373) wrote a number of letters in which he announced the date of Pascha, along with other instructions for or reflections upon the upcoming Paschal season. Theophilus (d. 412) did likewise and even provided a 100-year table to Theodosius I (347–395). We do not have this table, but we know that later authors referenced it as a basis for their own work and we have the Prologue that preceded it.28 In his explanation to the emperor, he reiterates the rules of celebrating after the equinox, celebrating on the Sunday after the fourteenth moon, and deferring this Sunday to the next week if the fourteenth moon happens to fall on a Sunday (Prologue 4, 6–7).29 Cyril (d. 444) also developed a ninety-five-year table out of the nineteen-year cycle spanning the years we know as 437 to 531, which he sent to Theodosius II (401–450).30 The Preface later attached to it by another author notes the now-standard range of dates for the Paschal full moon (March 21 to April 18) and for Pascha (March 22 to April 25; 10–11).31 Both tables are also notable for how they determined years as “X year of Diocletian” (the emperor from 284–305). This seems incredibly odd, since Diocletian instituted the last and worst official persecution of Christians by the Romans. Even so, the convention was founded on the reforms Diocletian made, which included forcing Egypt to follow the Roman consular year.32
The earliest attestation of the Roman customs appears in part 9 of the Chronography of 354.33 This calendar presents a list of Pascha dates from 312 to 411, which agreed with the eighty-four-year cycle eighty-five times and the Alexandrian cycle seventy-seven times (with an additional three times in which it seems that a compromise was made between Alexandria and Rome, but the list never agrees with Alexandria against the eighty-four-year cycle).34 This list ultimately shows an adherence to two or more methods of calculation that still found substantial—although hardly uniform—agreement with the preferred methods of both Rome and Alexandria.
A letter from Pope Leo I (~400–461) to a bishop named Paschasinus in 451 noted continuing discrepancy between Roman and Alexandrian Paschal dates, in particular noting that the problem with the calendar of Theophilus of Alexandria, which said that the Pascha would be on April 24, was contrary to Roman custom (Ep. 88.4).35 The reason for this custom is conveyed by the Chronicle of Prosper of Aquitaine (390–455) in a note on the year 444 (a rare year in which Pascha was celebrated on April 23). April 21 had been the day of Parilia for centuries, the day on which the founding of Rome was celebrated. As Mosshammer notes, “The church would want to avoid any intrusion into Holy Week of the sometimes wild festivities associated with the Parilia.”36
Around this time, a new figure burst onto the Roman scene: Victorius of Aquitaine. Little is known of this man apart from his Paschal cycle, which he produced in 457, at the commissioning of the archdeacon (who would soon be pope) Hilarius (d. 468).37 What is significant about his work is that he changed the Roman custom by rejecting the eighty-four-year cycle in favor of a nineteen-year cycle and he ignored the traditional Roman limits for Pascha dates. However, he retained the Roman tradition that Pascha could be celebrated on the sixteenth through twenty-second moons, as opposed to the Alexandrian limits of the fifteenth through twenty-first moons. He also projected his cycles for 532 years, which covered all possible repetitions of the table. After all, 532 is the product of 28 and 19, 19 being the number of years used in this cycle to get a whole number of lunar months, and 28 being the number of years for a solar cycle in the Julian calendar (the solar cycle is the interval between times when all the dates of the year will fall on the same days of the week; if January 1 is on a Sunday and March 1 is on a Wednesday, it will be twenty-eight years before every day on the calendar falls on all the same days of the week). As such, 532 years is the interval between two years that will be identical with regards to both the solar and lunar cycles.38 Some aspects of this scheme remained influential for centuries, it enjoyed initial success in the Roman world when Hilarius became pope in 461, and it had some lasting success in Victorius’s native Gaul (where the Fourth Council of Orleans [541] decreed adherence to his calendar) and the British Isles.39
But Victorius’s scheme had more than its share of critics over the years, and it never found any particular success in the East.40 He had allowed the possibility of the Paschal full moon to fall as early as March 18 and as late as April 17, which fit with neither Alexandrian nor Roman traditions. He also did not produce an unambiguous table. As Faith Wallis observes,
He set out his own table of Easters, listed beside them the “Greek” Easters, and invited the Pope to choose in cases of conflict. But Victorius’ “Greek” Easters were not, in fact, the Alexandrian dates; they were dates arrived at through Victorius’ own rules, and not observed anywhere in the Church. Ironically, his “Latin” Easter dates were often identical with the Alexandrian dates, because his insertion of the saltus in year 6 cancelled out the discrepancy between his lunar limits for Easter, and those of the Alexandrian Church. Therefore if the Pope chose to celebrate the “Latin” Easter as recorded in Victorius’ table, he would, in years 7–19 of the cycle, in fact be choosing the Alexandrian Easter date.41
A major reason for this discrepancy was that the year in which he began his nineteen-year cycle was year 7 in the Alexandrian cycle. He had attempted to establish his cycle in the time of creation, on which he followed the tradition of dating the first day to March 25 and the first full moon on the fourth day of March 28 (with a tabular date of March 29). As such, the first year of his table corresponded to 25 CE, year 4 corresponding to 28 CE (when he dated Jesus’s crucifixion to March 25 [with a tabular date of March 26]), and year 14 corresponding to year 1 of the Alexandrian cycle. As much as he tried to make such a firm foundation for his table, it was riddled with too many problems to supplant the more elegant and consistent Alexandrian table circulating at the time. It was this latter table that our next big name sought to continue.
Dionysius Exiguus (470–544) was this heir of the Alexandrian legacy, although he is best known for his use of the Anno Domini (AD) dating system, which is meant to track the number of years since the Lord’s Incarnation, and its derivative Common Era, which have influenced Western calendars to this day.42 As a renowned translator of texts from Greek to Latin, Dionysius was a fine candidate for continuing the Greek Alexandrian system in the West. Indeed, it is to Greek sources that he owes the basis for his AD system. After all, Dionysius never argues for his AD system or presents calculations to justify it. He uses it as an assumption that he could build upon. As Mosshammer states in his conclusion:
Dionysius Exiguus did not calculate or otherwise invent a new Christian era…. It is rather the case that Dionysius adopted his era of the Incarnation from the Alexandrians with their 19-year Paschal cycle. It was the Christian era of Julius Africanus, adopted by Anatolius of Laodicea, and transmitted along with the 19-year cycle to Athanasius, Andreas, Theophilus, Panodorus, and the Armenian church, as well as to Dionysius Exiguus.43
And indeed, it was both the reckoning of the Christian era and the nineteen-year cycle that Dionysius played a key role in establishing that served as a unified system across (at least most of) the Christian world.
Dionysius produced a ninety-five-year table to cover the next ninety-five years after Cyril’s similar table ended (i.e., 532–626). From the left to right, the columns cover the year according to the AD system, the indiction year (the Roman bureaucratic cycle of fifteen years used in the reigns of Diocletian, Constantine, and beyond for the non-ecclesial calendar), the epact for the year (specifically, for January 1), the concurrent (what day of the week March 24 fell on; see Bede, The Reckoning of Time 53 for more detail), the given year in the nineteen-year lunar cycle, the date of the Paschal full moon, the date of Pascha Sunday, and the day of the moon on Pascha Sunday. We see once more that the table follows the Alexandrian limits for Pascha between the fifteenth and twenty-first moons of the first lunar month, the dates always fall after the equinox and between the days of March 22 and April 25. This table provided a certain clarity, elegance, and definiteness that made it more attractive than Victorius’s table to people like the Venerable Bede (more on him later). He also provided a collection of arguments to explain the mathematical reasoning behind this table.44 However, the sixteen arguments that accompany the table today are not all original to Dionysius, as some have added their own notes to this text over the years. The arguments most likely original to Dionysius are §1 and 2 of Argument 1, Argument 2, §1 of Arguments 3 and 4, Arguments 5–6, 8, and §1 of Arguments 9 and 10.45 The fact that the many additions were made attests to the significance and popularity of this text, especially with the explanation of Argument 14 on how to determine what day of the week the fourteenth (Paschal) moon will fall.
Yet, in contrast to Victorius, Dionysius’s work did not receive any officially sanctioned status for many years thereafter. He had several admirers and someone (named Felix of Ghyllitanus) who continued his table when it expired in 626, but it was largely unknown, “we have no idea when exactly the Roman Church began to adapt its Easter calculations to the Dionysian table. It is interesting to observe that while the Irish, by Columbanus’ day, had heard of Victorius, they seem not to have known of Dionysius.”46 The West eventually underwent a shift in this regard around the time of the Synod of Whitby.
The Synod of Whitby (664) was called by King Oswiu of Northumbria to address several issues common in his kingdom and others of the British Isles. One of those issues was how to calculate the time for celebrating Pascha. Our two chief sources for this synod are Stephen of Ripon’s Life of Wilfrid 10 and the Venerable Bede’s more extensive Ecclesiastical History of the English People 3.25. As noted previously, Victorius’s work was popular in the area, but so was an eighty-four-year cycle (Bede, Ecclesiastical History 2.2, 19; 3.3–4, 17). The aforementioned Latin translation of Anatolius’s work was also in use at this time to support the eighty-four-year scheme over and against both Victorius’s work and the nineteen-year cycle in general that Anatolius had originally presented. This cycle used lunar limits from the fourteenth to the twentieth moons (for reasons Columbanus stated in n. 39) and allowed for Pascha to fall between March 26 and April 23. But by this time, another cycle had arrived from Rome: the one based on the work of Dionysius. Some of the old tropes play out as one side portrays its practice as going back to John and the other side portrays its practice as going back to Peter and Paul and as being observed throughout the world, hence why the Roman reckoning is represented as the “catholic” one. Wilfrid—who represents the Roman tradition—also criticizes Colman—who represents the British traditions—for claiming to follow the Law in his Paschal tradition, but excluding the twenty-first moon from the range, even though this is allowed by the Law (at least in terms of the Feast of Unleavened Bread). Both representatives appealed to Anatolius, but Colman appealed to the Latin version while Wilfrid appealed to the original nineteen-year cycle. Bede portrays this synod as a victory for the Dionysian reckoning (not least because it was argued to be based on universal tradition extending from Peter and based on his primacy among the apostles) and it was indeed a key event in the popularization of the Dionysian computus, but even Bede recognized that it was not a decisive victory (Ecclesiastical History 3.4; 5.15, 21–22).47 Victorius’s work would continue to be used by some well into the eighth century, even beyond the time of Bede’s writing.48 The Irish eighty-four-year cycle would also not disappear until the eighth century.49 But both would eventually fade away in favor of the Dionysian method, especially due to the work of the Venerable Bede himself.50
Bede (672/3–735), the father of English history, was ultimately responsible for the popularization of Dionysius’s AD system through his own chronological work and he was also essential to the establishment of Dionysius’s cycle in the West.51 He clearly had a profound interest in historical, chronicling, and computistical work, as seen in his early On Times (703), his The Reckoning of Time (725), and his magnum opus Ecclesiastical History of the English People (731). In On Times, we see him lay the foundation for his later work by his connection between the Paschal cycle (which is tailored to the Dionysian table and its AD system) and his exposition on the ages of the world (11, 13–14, 16–22).52 In between, he summarizes well the popular theological justifications for the timing of Pascha that had accreted to his day:
But in the former case [of Pascha as opposed to Christmas, with its fixed date] the mysteries of the life to come should be celebrated and its gifts received, and that is why Easter is called ‘Pasch’, which signifies the transition from death to life. Easter likewise seeks a season which corresponds to these mysteries: first, so that, with the equinox passed, the darkness of death may be conquered by the true Light; then, so that the joys of the new life may be celebrated in the first month of the year, which is called the month of the new [grain][Exod 23:15; 34:18]; third, so that the Resurrection, which took place on the third day and was revealed in the third era of the world – that is, under grace since before the Law and under the Law it lay concealed within a prophetic enigma – might be celebrated in the third week of the moon, since this very shift of phases of the moon at this time teaches the contemplative powers of the mind to exchange earthly things for heavenly glory; and finally so that the Lord’s day may be called to mind, a day made worthy of veneration through the creation of glorious light and through the triumph of Christ, and also a day which we should long for because of our own resurrection. (15)53
The connection between these two parts of his work and the theological undergirding would play essential roles in the aforementioned popularization, as the two noted works on time were crucial to the early days of the genre of the computistical manual, which would be used to teach others about Paschal computus.54 He would go on to explain Dionysius’s table in much more detail in The Reckoning of Time 44–65, including the lunar and solar epacts (50–57), when the common and embolismic years are in the cycle (44–45), the AD system (47), and the formula for determining the Paschal full moon (59–60). He also provides an allegorical interpretation of Pascha, at which point he launches into an extended version of the type of theologizing shown in the quote above (63–64), as well as a summary of the Paschal cycle (which he extends to twenty-eight iterations of the nineteen-year cycle or 532 years; 65; cf. Ecclesiastical History 5.21) before presenting his world chronicle in ch. 66. Wallis notes that this combination was designed to defend the Dionysian reckoning by making it the foundation for a work on reckoning time in general, “So lucid, thorough and well-organized was Bede’s exposition, so easy was it to teach from and learn from, that it can be said to have not only guaranteed the ultimate success of Dionysius’ system, but to have made computus into a science, with a coherent body of precept and a technical literature of its own.”55 As a result of his efforts, the Dionysian/Alexandrian system was further established as the virtually universal way for medieval Christians to reckon the time of the Pascha.
The exploration could continue after this point, but for the one person reading this who wants to know the complexities of medieval Paschal/Easter computistical works, I advise reading through the proceedings of the various meetings of the International Conference on the Science of Computus. Suffice it to say that the nineteen-year cycle became the dominant method for computing the date for Pascha. Even apart from the various supports from politics (especially in the East, but eventually in the West as well) and prestige (especially as attached to Alexandria), the nineteen-year cycle became the established method because it was the most accurate method available, given the science and established parameters of the time. As noted above, when accounting for the differences between the lunar and solar calendars, such that dividing the days in a solar year by lunar months, the remainder according to the mean tropical year (.3683) or the Julian year (.3685) is best approximated by the nineteen-year cycle compensating for the difference with seven embolismic years (7/19 = .3684), rather than the eight-year cycle with three embolismic years (3/8 = .3750) or the eighty-four-year cycle with thirty-one embolismic years (31/84 = .3690). Given that these calendars needed to be forecasted years in advance, the preference was to work on the basis of “mean” astronomical movements, as opposed to on the basis of regular astronomical observation. When one considers the logistics of forecasting Easter, adjusting ecclesiastical calendars for millions of people in a variety of nations with a variety of schedules, and trying to notify them of both the forty-day Lenten fast and the fifty-day Paschal season, it makes sense why it is easier to chart the Paschal season with roughly accurate calculations and make occasional corrections rather than try to be over-precise. Given these demands and given the parameters of finding the first Sunday after the first full/fourteenth moon that falls on or after the vernal equinox, the nineteen-year cycle provided the best forecasting tool available for correlating the lunar calendar with the Julian calendar. Unfortunately for the computists, the Julian calendar itself would pose a problem. We will explore why next time, as we see how Easter was a major motivating force in the creation of the Gregorian calendar.
While some call the Jewish calendars “lunisolar,” since they do actually keep up with the solar year by adding a thirteenth lunar month every few years, I follow Sacha Stern in referring to them as “lunar,” “because their solar component is marginal by comparison with their mainly lunar nature. Truly lunisolar calendars, where the lunar and solar elements are more or less on a par, can only be found in Qumran and related sources” (Sacha Stern, Calendar and Community: A History of the Jewish Calendar Second Century BCE—Tenth Century CE [Oxford: Oxford University Press, 2001], 1).
On the different Jewish calendars prior to and during the early church debates, see ibid., 2–21, 28–46, 50–62, 75–79, 85–97, 132–54, 155–210.
Ibid., 50–53.
Ibid., 78–79, 119.
Mosshammer, Easter Computus, 185.
Stern, Calendar, 75–78. On textual problems with this list, see ibid., 126–29.
For more on rabbinic reckoning, see Beckwith, Calendar and Chronology, 282–89.
Note that this critique does not concern the biblical provision of a Passover in the second month for those who were unable to keep the first one (Num 9:1–14). This provision is otherwise cited in support of Christian practice for when they celebrate Pascha.
For more on these letters, see Roger Beckwith, Calendar, Chronology, and Worship: Studies in Ancient Judaism and Early Christianity, AJEC 61 (Leiden: Brill, 2005), 8–14.
Beckwith, Calendar and Chronology, 68–69.
As I use computistical terminology throughout, I will try to give simple definitions, but if the reader finds my definitions insufficient or confusing, I recommend this glossary: http://digital.library.mcgill.ca/ms-17/fetchfoliodoc.php?target=Glossary.
I owe this helpful explanation for the different cycles to Faith Wallis, trans. and ed., Bede: A Reckoning of Time, TTH 29 (Liverpool: Liverpool University Press, 1999), xli–xliii. Also see Mosshammer, Easter Computus, 52–55.
On Africanus’s use of the nineteen-year cycle in his larger work, see Mosshammer, Easter Computus, 418–20.
See the extensive review of ibid., 204–39.
For more on the Hippolytan problem, see ibid., 118–21.
Ibid., 117; Thomas C. Schmidt, “Calculating December 25 as the Birth of Jesus in Hippolytus’ Canon and Chronicon,” VC 69 (2015): 547.
Mosshammer, Easter Computus, 121–25.
George Ogg, ed. and trans. The Pseudo-Cyprianic De Pascha Computus (London: SPCK, 1955).
Mosshammer, Easter Computus, 125–27.
On the question of if a later bishop of Alexandria, Peter (d. 311), used an eight-year cycle, see ibid., 127–29.
Ibid., 136–39.
Ibid., 136.
Ibid., 140–45.
For more on this synod, see https://www.fourthcentury.com/the-council-of-arles-ad-314/.
In common parlance, Jews now refer to both the day of Passover and the subsequent celebration of the Feast of Unleavened Bread as Passover/Pesach. For the purposes of my analysis, I restrict reference to “Passover” to the day of Passover according to biblical instruction. After all, if this distinction between these two feasts is collapsed, it has almost certainly happened as many as hundreds of times that Christians celebrated Pascha Sunday in the midst of the Feast of Unleavened Bread.
It is not possible to confirm if and where these dates applied, but the calculations at https://www.staff.science.uu.nl/~gent0113/easter/easter_text2a.htm indicate that this preceding or coinciding could have happened in 326, 343, 346, 347, 350, 367, 370, 374, 394, 401, 414, 418, 421, 441, 445, 465, 475, 495, 496, 499, 519, 523, 536, 543, 563, 570, 590, 594, 614, 743, and 783.
Mosshammer (ed.), Prologues.
Theophilus also tries to explain how celebrating the Pascha so long after the fourteenth moon could still be consistent with the OT directives regarding the Passover (11).
For the table, see Mosshammer (ed.), Prologues, 171–73.
On authorship, see ibid., 133–38.
Mosshammer, Easter Computus, 172–78.
Available online at http://www.tertullian.org/fathers/chronography_of_354_09_paschal_cycle.htm.
For a comparison, see Mosshammer, Easter Computus, 214–16.
On another occasion, in 455, Leo indicates the West’s acceptance of the Eastern date for Pascha (Ep. 142).
Mosshammer, Easter Computus, 170.
The text is not translated in English, but can be found in Bruno Krusch, Studien zur christlich-mittelalterlichen Chronologie: Die Entstehung unserer heutigen Zeitrechnung, Abhandlungen der Preussichen Akademie der Wissenschaften, Jahrgang 1937, Phil.-hist. klasse 8 (Berlin: Akademie der Wissenschaften, 1938), 16–52. An older edition is available online through searching https://www.dmgh.de/ (Theodor Mommsen, Chronica Minora, vol. 1, Auctores Antiquissimi 9 (Berlin: Weidmann, 1892), 669–835.
For more on Victorius’s work, see Mosshammer, Easter Computus, 239–44; Wallis, introduction, l–lii.
On the use of Victorius in the latter region, see Masako Ohashi, “The Easter Table of Victorius of Aquitaine in Early Medieval England,” in The Easter Controversy of Late Antiquity and the Early Middle Ages, Its Manuscripts, Texts, and Tables: Proceedings of the 2nd International Conference on the Science of Computus in Ireland and Europe, Galway, 18–20 July, 2008, ed. Immo Warntjes and Dáibhí Ó Cróinín, STT 10 (Turnhout: Brepols, 2011), 137–49. Even there, where the nineteen-year cycle took some time to become established, a figure as popular as Columbanus (543–615) sent a letter to Pope Gregory I (540–604) near the end of the sixth century that included a critique of Victorius’s scheme (Ep. 9.127 [NPNF2 13:100–107]). According to Columbanus, Victorius had introduced an error that allowed the Christian Passover to be celebrated before the vernal equinox and on the 21st or 22nd day of the moon, when nights would be darker for longer, and which went beyond the dates of the Passover as prescribed in the Torah.
For the purposes of this analysis, I do not pursue the history of Paschal computus in the East. For more information on that history, see Mosshammer, Easter Computus, 245–316.
Wallis, introduction, lii.
For more on his work than I can provide here, see Mosshammer, Easter Computus, 59–106. For how his dating system built on others, see pp. 339–437. An English translation of his Paschal cycle, with accompanying arguments is available online at http://www.tertullian.org/fathers/dionysius_exiguus_easter_01.htm.
Mosshammer, Easter Computus, 437.
The logic, however, is not always easy to discern in mathematical terms. Fortunately, Immo Warntjes has articulated these arguments in the form of equations (“The argumenta of Dionysius Exiguus and Their Early Recensions,” in Computus and Its Cultural Context in the Latin West, AD 300–1200: Proceedings of the 1st International Conference on the Science of Computus in Ireland and Europe, Galway, 14–16 July, 2006, ed. Immo Warntjes and Dáibhí Ó Cróinín, STT 5 [Turnhout: Brepols, 2010], 45–53). The online edition linked above also translates into equations, but the analysis there is more convoluted.
Ibid., 40–96.
Wallis, introduction, liv.
The decision here was confirmed at the Synod of Hertford in 672 (Ecclesiastical History 4.5).
Ohashi, “Easter Table,” 137–49; James T. Palmer, “Computus after the Paschal Controversy of AD 740,” in The Easter Controversy of Late Antiquity and the Early Middle Ages, Its Manuscripts, Texts, and Tables: Proceedings of the 2nd International Conference on the Science of Computus in Ireland and Europe, Galway, 18–20 July, 2008, ed. Immo Warntjes and Dáibhí Ó Cróinín, STT 10 (Turnhout: Brepols, 2011), 213–41.
Daniel McCarthy and Dáibhí Ó Cróinín, “The ‘Lost’ Irish 84-Year Easter Table Rediscovered,” Peritia 6–7 (1987–1988): 227–42.
One work that I was not able to attend to here that was influential on Bede is Isidore of Seville’s Etymologies 6.17, which provides a much shorter presentation of the dominant tradition than Bede’s work.
For more, see Máirín MacCarron, Bede and Time: Computus, Theology and History in the Early Medieval World (London; New York: Routledge, 2020), 136–56.
Calvin B. Kendall and Faith Wallis, ed. and trans., Bede On the Nature of Thing and On Times, TTH 56 (Liverpool: Liverpool University Press, 2010).
Ibid., 117.
For more on the linkage between these different parts of his work, see MacCarron, Bede; Wallis, introduction.
Wallis, introduction, xvii.