The Stones of Easter: Lithic Inscriptions of the Easter Calendar in the Late Ancient and Late Medieval Eras
Steven L. Ware, Ph. D.
VI. Internationales Symposium
“Mittelalterliche Astronomische Großuhren”
26 Oktober 2012
Rostock, DE
How does one document the most important event in all of human history? In the world of the twenty-first century, of course, we would have TV news crews assigned to cover the event from every possible angle. Anyone fortunate enough to be at the scene would be busily snapping pictures with their personal camera or cellphone, and offering commentary. But what if that event took place nearly 2,000 years ago in a remote and rebellious corner of the Roman Empire? And what if it was just a small handful of common, unknown, uneducated, and unremarkable people who understood the importance of this event? Yet that was exactly the case with the beginning of Christianity, and the event that became known as Easter, or Pascha. As the earliest Christians sought to proclaim and live out the implications of that most important event in human history—the death and resurrection of the Messiah Jesus, which offers forgiveness of sins to all who believe—they nevertheless sought a way of retaining the proper calendrical date for its celebration.
If I may include a brief personal note, one of those matters of personal uniqueness which my parents shared with me at an early age was the fact that I had been born on Easter Sunday morning. With a birthdate in early April, it was therefore my first assumption that my birthday would be on Easter Sunday every time it occurred on a Sunday. When I later discovered my error, I began asking those calendrical questions which led me slowly but surely to the present study. Why is it that Easter is not on the same calendar date every year, or even on the same Sunday? I found the beginnings of the answer to that question in Scripture—which is where I tell students to go today. What does Scripture tell us? All four Gospels of the New Testament state clearly that the crucifixion of Jesus took place at the time of the Jewish feast of Passover, and that his resurrection occurred on the following Sunday morning.
While the earliest generations of Christians likely considered every one of their worship gatherings a celebration of Jesus’ resurrection—especially on Sundays—when they did begin to think ahead in terms of celebrating the actual day of Jesus’ resurrection, they immediately confronted the dual calendrical conundrum: First of all, they had to keep in mind that Passover occurs every year on the Hebrew calendar date of 14 Nisan. Like most ancient calendars up until the creation of the Julian calendar by the Romans in the first century BC, the Hebrew calendar was lunar-based. This meant that for Jews of Jesus’ lifetime the normal expectation was that a “year” consisted of either twelve lunar cycles (355 days), or thirteen lunar cycles (384 days). The determination of which years were common (with twelve lunar cycles) or embolismic (with thirteen cycles) was regulated by the commonly-understood nineteen-year-long Metonic Cycle invented by Greek astronomers in the fifth century BC.
The other half of this calendrical conundrum was, of course, the strictly solar Julian calendar of the Romans. The councils of Arles (AD 314) and Nicea (325) both affirmed the practice of celebrating Jesus’ resurrection on a Sunday, and therefore settled the Quartodeciman controversy. But the question of the precise date of Passover from year to year on the Julian calendar, and therefore of the correct Sunday for the celebration of the resurrection, was more difficult and hence longer in its resolution. This was especially the case in those regions where Christianity had far outgrown the social and geographical bounds of its origins in Judaism—particularly in the western Mediterranean, where some Christian congregations were hundreds of miles from the nearest synagogue.
It is no wonder, then, that a variety of Paschal calendars was developed by Christians during those first several centuries. It has been estimated that during the late ancient and medieval periods several hundred paschal calendars were published in books and annals.[1] By contrast, the complete collection of Easter calendars inscribed on stone and wood surviving from the entirety of Christian history numbers less than a dozen items scattered across Europe and Africa. This begs the question of the particular history of each of these stones and the content of their inscriptions. It also begs the question of the political, social, and economic conditions of the occasions and locations in which they were constructed.
This paper reflects the initial efforts of this writer to understand this small piece of the history of paschal calendars. For the purposes of this short presentation the primary emphasis has been placed on the content of the inscriptions, although much more can be said about the wider contextual matters. The inscriptions themselves have been separated into three historical categories: The first category consists of the stones surviving from the late ancient era, approximately AD 200-550. The second category consists of the meridiane created in several Italian churches from the late fifteenth through early eighteenth centuries. The third category consists of the ecclesiastical calendar discs attached to astronomical clocks in church buildings during the fourteenth through sixteenth centuries, such as the beautiful example residing with us here at Rostock. While a uniformity of material or perspective is not expected between the variety of places and times represented by these categories of inscription, it is nonetheless notable that they possess some continuity of information as their authors sought to document what they perceived as the most important event in human history. This and other factors lead this writer to conclude that these stones of Easter represent some significant high points in the history of Christian development of the computus and therefore of public celebration of the resurrection of Christ.
I. Ancient Stones of Easter: Documenting the Divine
A. Ostracon #4554
While the writings of perhaps a dozen or more authors of the first several centuries of the Christian era bear witness to the efforts of Christians to properly schedule their annual celebration of Jesus’ resurrection from the dead, that witness is likewise borne by only three stone inscriptions of the same period. The first of these hardly qualifies as a paschal calendar at all, yet its fragmentary information testifies nonetheless to the existence of early paschal calendars among Christians (whether on stone or paper), and especially to debates among Christians over the proper date of the Easter feast.
Nothing more than a chip of ancient limestone, Ostracon #4554 at the Coptic Museum in Cairo offers evidence of the widespread popularity of Quartodecimanism. From the Church History of Eusebius of Caesarea (AD 263-339), we learn that in the late second century it became the practice of Christians in the province of Asia (modern western Turkey) to celebrate both the death and resurrection of Christ on the “fourteenth day of the moon” (eve of the fourteenth day), thereby remaining faithful to the date of Jesus’ crucifixion on the fourteenth day of Nisan (Passover).
From Eusebius we learn that this practice led to a lengthy period of rancorous debate which was not quickly resolved, since it was the predominant practice of Christians elsewhere to celebrate Jesus’ resurrection on the Sunday after Passover.[2] A relatively final decision on the matter was made at the Council of Arles in AD 314 and reaffirmed at Nicea in 325[3], asserting that the resurrection of Christ should be celebrated only on a Sunday, although some Christians in Asia continued their practice for another century.
The ostracon at Cairo, however, is evidence that Quartodecimanism may well have had many followers on the south shore of the Mediterranean as well. The recto of the stone contains eight lines which feature repeated use of abbreviated versions of the Greek words μήν (meaning both “moon” and “month”), δέκα (“ten”), and τέσσαρες (“four”), referring to the fourteenth day of the moon, or Passover. The verso of the stone, on the other hand, contains a series of Egyptian calendar dates for the full moon following the spring equinox. The last five of these match the dates of the Paschal full moon for the years AD 328-332, which are known from the annual Easter letters written by Bishop Athanasius of Alexandria (326-373). It has been therefore surmised that these lines were very possibly penned by their author in the early fourth century, although a set of only five dates “may be too few to demonstrate that the years in question are identical.”[4]
B. The Sarcophagus of Hippolytus
The second ancient stone of Easter more properly fits the given category as an Easter calendar stone. It is attributed to Hippolytus (ca. 170-235), and is inscribed on the sides of his sarcophagus, which is located at the Vatican Museum in Rome. As bishop of Portus (near Rome) in the early third century—before there was a universally recognized method for calculating the dates for Easter—he was responsible for the proclamation and dissemination of this vital information. For the benefit of posterity, therefore, what was undoubtedly viewed as one of the more important accomplishments of his office is the 112-year cycle of both Easter and Passover dates which are inscribed on the two major side panels below the seated figure.[5]
On the figure’s left side is the 112-year cycle of Easter dates, corresponding to the years AD 222-333. The dates are arranged vertically in seven blocks of sixteen years each, perhaps an indication of a doubled ὀκταέτερις (octaeteris = eight-year cycle), commonly used in previous centuries by the Greeks. On the figure’s right side is an equally engaging 112-year cycle of Passover dates. Again, it is arranged vertically in seven blocks of sixteen years each, with letters of the alphabet designating the day of the week upon which Passover was to occur in a given year. Perhaps even more interesting, however, are the notations found inscribed beside several of the Passover dates which refer to historical events of Christian interest. For instance, beside the letter denoting the second year of the first cycle is an inscription stating ΓΕΝΗΣΙΣ ΧΣ (“Genesis Christos”) for the Passover date of 2 April (IV Nones April). This could be interpreted as Hippolytus’ choice of 2 April as Jesus’ birthdate, although it is just as likely that he was referring to the incarnation, meaning that Jesus was conceived in the womb of his mother Mary on 2 April and was born approximately nine months later. But it is equally important to note that the year for which the notation is apparently given is AD 223. Subtracting two complete 112-year cycles from 223—depending upon which date is chosen as the beginning of a new year—brings us to 2/1 BC.
A second notation of great interest for Christians are the words ΠΑΘΟΣ ΧΣ (pathos Christos), or “passion of Christ” beside the last date of the second sixteen-year cycle. This inscription is exactly thirty years past the first inscription, and would therefore imply Hippolytus’ belief 1) that the life of Christ was thirty years in length, and 2) that his death occurred in AD 29. In addition, these and the several other inscriptions next to Passover dates imply his belief that the dates for both Passover and Easter would repeat themselves every 112 years.[6]
While this belief is demonstrably incorrect, and while his 112-year cycle was later superseded with more accurate Paschal calendars based on the 532-year master calendar cycle, the inscription of Hippolytus nevertheless marks a significant historical moment in the development of Paschal calendars. The fact that these calendrical computations were inscribed on the funerary monument of a leading Christian bishop of the era testifies to the size and social influence of the Christian community in and around Rome in the early third century, even in spite of periodic imperial persecution. In addition, the fact that these dates were inscribed in stone for the viewing pleasure of future generations testifies to the confidence of Christians in Hippolytus’ generation that these dates were indeed correct, that they were a reliable indicator of the calendar by which Christians would celebrate what they perceived as the most important event in human history.
C. Dionysius’ Paschal Cycle in Stone
In AD 525, a monk living in Rome by the name of Dionysius Exiguus was given the assignment—apparently by the papal office—of constructing a new calendar of dates for the celebration of the resurrection of Christ. The consequent ninety-five year cycle created by Dionysius covered the years known as AD 532-626, and succeeded the previous cycle of Cyril of Alexandria which was near expiration. Dionysius is more widely known, of course, for his creation of a new dating system based upon the approximate birthdate of Christ, which in the succeeding centuries slowly became the dominant numbering system under which most of the human race now dates itself and understands its past and future.[7] While the tale of humanity’s quest to create an accurate calendar certainly has a legitimate history of its own, in which Dionysius is one of many important players, what should not be forgotten is the parallel story featured here—of the efforts of Dionysius and other Christian scholars over the centuries who endeavored to create accurate calendars of Easter.
For the purposes of this essay, moreover, what is remarkable is a curious evidence of Dionysius’ work which remains at Ravenna today in the Archiepiscopal Museum—an inscription of his Paschal cycle on a large marble slab. In a circular rosette style, it is divided into nineteen sections (resembling leaves/petals) for the nineteen years of the Metonic cycle. Flowing from the cross at the center, each set of years is designated as either “common” (having twelve lunar cycles) or “embolismic” (thirteen lunar cycles). Then beginning from the outer edge, each section lists the five years of Dionysius’ cycle which correspond to that stage of the Metonic cycle, and the date of Easter for each year. Likewise included are the annual dates of Passover and the age of the moon on Easter Sunday.
While little is known about the history of the stone itself, its very limitation to the ninety-five years of Dionysius’ cycle is a sure indication that it was inscribed shortly after his creation of the cycle itself. In addition, the impressive physical size of this calendar (approximately three-feet square) and its location at Ravenna (the western capital of Byzantium in the sixth century) are very likely indicators of its importance—that it was displayed prominently for use by ecclesiastical authorities.[8] To an equal degree, therefore, if not an even greater degree than the older inscriptions on the sarcophagus of Hippolytus, this stone makes two notable statements about Christians living in and around Ravenna three centuries later. First of all, the size and location of this inscription testifies to a large and publicly-oriented Christian population that wishes to share with the world its message of the death and resurrection of Christ. Secondly, the inscription of these calendrical details in stone again testifies to their confidence in the accuracy of the details, and therefore to their confidence in the accuracy of their own grasp of astronomical knowledge.
II. A Simple Line with a Not-so-simple Purpose: The Meridiana
No social institution of western civilization was challenged more deeply by the events and processes of the early modern era (roughly 1400-1800) than the Roman Catholic Church. The artistic and philosophical challenges of the Renaissance, the theological and organizational challenges of the Protestant Reformation, and the scientific and political challenges of the Enlightenment all combined to bring into question many of the practices and assumptions of Catholicism, and motivated it toward several reforms. One notable reform in the midst of this era was the proclamation of the Gregorian calendar in 1582. Astronomers were universally agreed for centuries on the inaccuracies of the old Julian calendar and had proposed revisions to Rome. But the popes were nevertheless reluctant to move ahead with a calendrical revision—specifically because of its effect on the annual date of Easter. Since Easter was inextricably linked to not only the date of Passover but also the vernal equinox, any calendrical revision brought into question the paschal calendars of the era.
One simple scientific instrument which was instrumental in this reform is the meridiana, or meridian line.[9] A meridiana is at its core a simple line which performs a function inside a building similar to that accomplished by a sundial outside a building. It tells time, yet not in the same way. Rather than measuring the changing angle of the sun in its daily passage across the heavens from east to west, a meridiana is a line oriented north-south to note the sun’s changing angle toward a particular location at a particular time each day. This angle changes as the Earth proceeds through its annual orbit and its inclination of nearly 23.5˚ on its axis causes the variations of light and temperature.
A few meridiana had been installed in the floors of Italian churches already before the Gregorian revision of the calendar. Most notable among these is the line at the Cathedral of San Petronio in Bologna, which had been only recently installed by Ignazio Danti (1536-1586) in 1575. Because of Danti’s success, he was soon appointed by Gregory to the calendrical commission, where he played at least a minor role. A final meridiana was installed in an Italian church in 1702, this time in Rome. Its location was in the Basilica church of Santa Maria degli Angeli, which until 1560 had been simply the ruins of the Baths of Diocletian. Nearly one and one-half centuries after its conversion into a church to honor the Christians who had been martyred by Diocletian, Pope Clement XI commissioned Francesco Bianchini (1662-1729) to build a meridiana to symbolize the victory of his predecessor Gregory’s Christian calendar over the old pagan Julian calendar.
Although the gnomon at Santa Maria degli Angeli is not as high and the line not as long as that at Bologna, Bianchini’s meridiana was nevertheless constructed with minute attention to detail.[10] One of those details—admittedly the original reason behind the construction of all meridiane but curiously omitted at Bologna and elsewhere—was the notation of the Terminus Paschae, or the calendrical limits of Easter. For most modern observers, it is necessary to read the line somewhat backward calendrically. Proceeding from the summer solstice—the far south end of the line nearest the wall where the gnomon admits the beam of sunlight—and counting up to day fifty-five, one observes the unmistakable papal seal of Clement XI. Day fifty-five from (before) the summer solstice is 25 April—the latest possible date of Easter. Following northward the increasing numbers on the line brings one backward calendrically to day ninety before the summer solstice—at 22 March, thirty-five days before 25 April and the earliest possible date of Easter. Hence, from the perspective of simple observation, the riddle of Easter had been finally solved and documented by Bianchini’s meridiana.
III. Astronomical Clocks and Calendar Discs: Uniting the Sacred and Secular
This brings us to the third and final form of the Stones of Easter—the calendar discs attached to astronomical clocks in locations north of Italy, from the late fourteenth century onward.[11] Beginning in 1383 in Lyon and stretching through 1540 in Münster, these calendar discs and the clocks to which they are attached give a visible public witness of two things: First of all, they give obvious witness of the increasing astronomical knowledge of Europeans in the late medieval to early modern period, as well as their increasing confidence in the accuracy of their calculations. Secondly, these calendar discs give witness to the desire of their creators to place their astronomical knowledge within the larger context of divine activity in human history. By doing once more what early generations of Christians had sought to do—to document the timing of the most important event in human history, the death and resurrection of Christ—they gave ultimate meaning to their astronomical calculations by placing them within the divine cosmos.
In the interest of time and in this company, I will not take the time to engage in a thorough description of each of the calendar discs and their contents. (Some of the rest of us here could certainly do that much better than I.) At the very least, I must agree wholeheartedly with Schukowski’s assertion that the astronomical clocks are an example of “medieval high tech” (“mittelalterliches Hightech”[12]) due to both the exacting technology of their constituent parts and the several realms of knowledge brought together in their display. What I will do, however, is to take a moment to describe what I believe is a significant difference in the information presented on these calendar discs over against their ancient predecessor at Ravenna.
One notable difference between the calendrical information found on the calendar discs, such as the one residing with us here at Rostock, and their late ancient predecessor at Ravenna containing the calculations made by Dionysius Exiguus in the sixth century, is their orientation with respect to the Metonic cycle. The difference is twofold: First of all, the inscriptions at the outer edge of each of the “leaves” of the calendar stone at Ravenna show that the first year of Dionysius’ paschal cycle is linked to the seventeenth year of a previously-existing Metonic cycle. Consequently, the fourth year of Dionysius’ paschal cycle is linked to the first year of the Metonic cycle.[13] By contrast, on the calendar discs attached to the astronomical clocks the first year of each Metonic cycle has been synchronized with the first year of a paschal cycle. For instance, as we see on the calendar disc here in Rostock, our current year of 2012 is listed as year eighteen of the Metonic cycle. By simple calculation we will discover that 2012 is exactly 1,463 years after AD 549, which is the eighteenth year of the first cycle on Dionysius’ paschal calendar. 1,463 years is exactly 77 Metonic cycles. But on Dionysius’ table, AD 549 is listed as year fifteen of the Metonic cycle.
So the question must be asked: Why the difference? In other words, when was this change made, and why? First, a point of reference worthy of note is a further inscription on the marble slab just outside the leaf representing the ninth year of the paschal cycle—“DIVISIOCYC·LI·II” (“division of cycle 51, part II”). This means that Dionysius (or at least the author of the stone inscriptions) understood that his paschal cycle began with the fifty-first Metonic cycle since its origin, and that it was a combination of an eight-year cycle with an eleven-year cycle. Interestingly, if one subtracts exactly 51 Metonic cycles (969 years) from AD 535—the first date in Dionysius’ paschal table which is matched with the first year of a Metonic cycle—the result is 435 BC. This is the period when the Greek astronomer Meton and his associates in Athens designed the cycle which still bears his name.[14] Using 435 BC as a [corrected] baseline for counting Metonic cycles carries with it the implication that the sources used by Dionysius for his calculations pointed in this direction. Unfortunately, Dionysius did not specify his sources in this matter.
When was the change made, and why? While additional research is necessary for a final conclusion, the following assertions can be made: First of all, it is clear that Bede was still utilizing the Dionysian orientation two hundred years later when he wrote his De temporum ratione. His “532-Year Paschal Table” designated AD 532 and every other year at the beginning of a nineteen-year paschal cycle (AD 551, 570, 589, etc.) as the seventeenth year of the lunar (Metonic) cycle.[15]
Secondly, it is likewise clear that by the end of the eighth century in the realms of Charlemagne the change in orientation had already been made. Alcuin’s answer to the emperor and his advisors on a question concerning the observed age of the Easter full moon (in March) and its effect on the possible date of Easter includes the observation that AD 799 was the second year of the nineteen-year lunar cycle. Again, simple math tells us that AD 799 is 266 years after 533, or exactly fourteen Metonic cycles. AD 533 is shown on the Dionysian table as the second year of the paschal cycle, but the eighteenth year of the Metonic cycle. The assertion by Alcuin that AD 799 is simply the second year of the lunar cycle, without further clarification, is therefore an indication that the synchronization of the Metonic cycle with the paschal cycle had already been accomplished.[16]
While the exact date of the synchronization is unclear, it is certainly plausible that the adjustment was made as part of the Carolingian calendar reform only recently enacted.[17] The reasons behind the synchronization are also unclear, although it is equally plausible that Alcuin followed the example of Dionysius in suggesting a further Christian orientation to the calendar: In addition to constructing a new paschal cycle, Dionysius had asserted a (very possibly) new calendrical orientation around the concept of Anno Domini.[18] Similarly, it is equally plausible that Alcuin saw no further need to retain the pre-Christian Greek numbering for the Metonic cycle, and therefore synchronized it with the paschal cycle so that the year of the incarnation and birth of Christ was the first year of the cycle rather than the seventeenth.
A second difference between the paschal calendar of Dionysius and those attached to the astronomical clocks is the occurrence of the embolismic years within each nineteen-year cycle. As we can see once more on the calendar disc here at Rostock, 2014 will be an embolismic year, as evidenced by the fact that the date of Easter jumps forward twenty days from 31 March to 20 April. In addition, the Golden Number tells us that 2014 is the beginning of a Metonic Cycle. Once more, simple calculation tells us that 2014 is 1,482 years past AD 532, or exactly 78 Metonic cycles. AD 532 is the first year of Dionysius’ paschal cycle, and as we see on his chart it was not an embolismic year but a common year. By further observation we see that nearly 1,500 years ago when Dionysius made his calculations the Metonic pattern was to include embolisms in years 3, 6, 8, 11, 14, 17, and 19. By contrast, the modern pattern, as shown by the calendar discs on the astronomical clocks, includes embolisms in years 1, 4, 6, 9, 12, 15, and 17.
So again the question must be asked: Whence the change, and why? In this case, the answer is found in the consequences of the adoption of the Gregorian calendar reform in 1582. Close observation of the dates of Easter in the Metonic cycle already in progress at the date of the reform (AD 1577-1595) shows how adjustments were made: AD 1583—the first year affected by the reform—was the seventh year of the Metonic cycle and therefore would have been a common year according to the old pattern. It remained a common year in the new pattern, but since ten days were eliminated from October 1582, the date of Easter regressed by only five days rather than the usual eight or fifteen. The next year, 1584, contains an even more noticeable difference. Under the old pattern, as the eighth year of the Metonic cycle, it would have been an embolismic year. But with the elimination of the ten days one and one-half years previous there was no need for the embolism. So instead of vaulting ahead by twenty days, the date of Easter simply regressed another nine days and the year was common. In fact, observation of the Metonic cycle for 1577-1595 shows that only six embolisms were required rather than the usual seven—in years 3, 6, 9, 12, 14, and 17 (1579, 1582, 1585, 1588, 1590, and 1593). But it also required that the next Metonic cycle begin with an embolismic year (1596) in order to keep the date of Easter within the limits already established.
This also explains a major reason why Greek Orthodox officials and theologians rejected the Gregorian reform when informed by representatives from Rome, and why they have been very slow even to implement elements of it ever since. Although Orthodox leaders were equally aware of the faults of the Julian calendar, they were even more reluctant than their western counterparts to make any amendments to a practice that had endured more than a thousand years.
Clearly, further research into these questions, as well as the contextual matters surrounding the particular histories of each of these stones of Easter, will yield additional insights into these significant moments in the historical development of both western calendars in general and paschal cycles in particular. While my research thus far has focused on matters that may seem rather minute and remote from the concerns of most, these matters were certainly not remote from the concerns of earlier generations of Christians who sought to document and celebrate the most important event in human history.
Notes
[1] Evelyn Edson, “World Maps and Easter Tables: Medieval Maps in Context,” Imago Mundi 48 (1996): 25; http://www.jstor.org/stable/1151259.
[2] Church History V, 23-25, in NPNF 2, I, 241ff.
[3] NPNF 2, XIV, 54. The modern reader will no doubt note what appears to be an anti-Jewish tone in the words of Constantine—words which have sometimes come back to haunt Christians more recently. Without trying to defend Constantine, we should note that this is not only a reflection of Christianity’s rise to power in the late Roman world, but also of the bitter memory of many Christians who were ousted from Jewish communities. For more on the Quartodecimans, including some of their own statements, see Easter in the Early Church: An Anthology of Jewish and Early Christian Texts (Raniero Cantalamessa, ed. Collegeville, MN: Liturgical Press, 1993), 33-37, 46-50.
[4] S. Kent Brown, “An Easter on Limestone,” Acts of the Fifth International Congress of Coptic Studies; Washington, 12-15 August 1992 (1992): 89.
[5] For more on the history of the sarcophagus itself, see Allen Brent, Hippolytus and the Roman Church in the Third Century: Communities in Tension before the Emergence of a Monarch-Bishop (Leiden: E. J. Brill, 1995), 7-50.
[6] PG X, 875ff. Unfortunately, modern calendar converters show that Hippolytus’ faith in the 112-year cycle was unfounded, as the dates of Passover do not repeat themselves exactly after this interval. In addition, 2 April, 2 BC corresponded roughly to 28 Nisan, not the Passover date of 14 Nisan. Similarly, 2 April, 1 BC corresponded to 9 Nisan. Moreover, the most likely date of Jesus’ crucifixion is 3 April AD 33 (14 Nisan 3793).
[7] For a review of the calendrical work of Dionysius Exiguus and the several debates surrounding its construction, intent, and historical usage, see Steven L. Ware, When was Jesus Really Born: Early Christianity, the Calendar, and the Life of Jesus (St. Louis: Concordia, forthcoming), chapter five. See also Georges Declercq, Anno Domini: The Origins of the Christian Era (Brussels: Brepols, 2000); Alden A. Mosshammer, The Easter Computus and the Origins of the Christian Era (Oxford: Oxford University Press, 2008). The chronological works of Dionysius are found in PL LXVII.
[8] Little information on the history of the stone is given, except that the slab came from a quarry on the island of Proconnesus in the Sea of Marmara, near the coast of modern Turkey. One travel blog described this stone as “striking but indecipherable” (http://www.travel-wonders.com/2009/07/touring-mosaic-city-ravenna-italy-part_10.html). It is certainly striking, but far from indecipherable, as many of this writer’s students will attest.
[9] For more on the history and use of the meridiane, see Ware, chapter six. For more on the astronomical and mathematical theory behind their construction, see also J. L. Heilbron, The Sun in the Church: Cathedrals as Solar Observatories. Cambridge: Harvard University Press, 1999.
[10] Heilbron, 152ff.
[11] It should be admitted here that all of the calendar discs attached to astronomical clocks are actually made wood, not stone. I have nevertheless placed them in the same category as the other stones because they were made for the same purpose and therefore make the same kind of public statement: While the same categories of information can be found in numerous books and annals throughout the medieval and early modern periods, the calendar discs were placed deliberately in very public locations so that their information was available to a much wider spectrum of humanity than the few monks or scientists who would take the time to read the annals.
[12] Manfred Schukowski, Wunderuhren: Astronomische Uhren in Kirchen der Hansezeit (Schwerin: Thomas Helms, 2006), 9-10. In addition to thorough descriptions of each of the clocks in the Hanseatic cities, also included are several helpful appendices (125ff) giving historical and constructive details of all known astronomical clocks across Europe.
[13] For the paschal table of Dionysius Exiguus, see PL LXVII, 493ff; also found at http://hbar.phys.msu.ru /gorm/chrono/paschata.htm.
[14] Borst (Die karolingische Kalenderreform [Hannover: Hahnsche, 1998], 687) and others have asserted 432 BC as the beginning date for use of the Metonic cycle, although without lengthy explanation.
[15] Faith Wallis, Bede: The Reckoning of Time (Liverpool: Liverpool University Press, 1999), 392-404. Bede also affirms the continued use of Dionysius’ pattern for common and embolismic years (122-123).
[16] Kerstin Springsfeld, Alcuin’s Einfluß auf die Komputistik in der Zeit Karls des Großen (Stuttgart: Franz Steiner, 2002), 168-169.
[17] Borst (231ff) contends that the reform was begun with the work of Alcuin at Lorsch in AD 789. See also Monumenta Germaniae Historica (Hannover: MGH, 1883), I, 60; http://www.mgh.de/bibliothek.htm.
[18] Dionysii Exigui, “Epistolae Duae de Ratione Paschae,” PL (Montrouge: Parisiorum, 1848), LXVII, 19ff.
If I may include a brief personal note, one of those matters of personal uniqueness which my parents shared with me at an early age was the fact that I had been born on Easter Sunday morning. With a birthdate in early April, it was therefore my first assumption that my birthday would be on Easter Sunday every time it occurred on a Sunday. When I later discovered my error, I began asking those calendrical questions which led me slowly but surely to the present study. Why is it that Easter is not on the same calendar date every year, or even on the same Sunday? I found the beginnings of the answer to that question in Scripture—which is where I tell students to go today. What does Scripture tell us? All four Gospels of the New Testament state clearly that the crucifixion of Jesus took place at the time of the Jewish feast of Passover, and that his resurrection occurred on the following Sunday morning.
While the earliest generations of Christians likely considered every one of their worship gatherings a celebration of Jesus’ resurrection—especially on Sundays—when they did begin to think ahead in terms of celebrating the actual day of Jesus’ resurrection, they immediately confronted the dual calendrical conundrum: First of all, they had to keep in mind that Passover occurs every year on the Hebrew calendar date of 14 Nisan. Like most ancient calendars up until the creation of the Julian calendar by the Romans in the first century BC, the Hebrew calendar was lunar-based. This meant that for Jews of Jesus’ lifetime the normal expectation was that a “year” consisted of either twelve lunar cycles (355 days), or thirteen lunar cycles (384 days). The determination of which years were common (with twelve lunar cycles) or embolismic (with thirteen cycles) was regulated by the commonly-understood nineteen-year-long Metonic Cycle invented by Greek astronomers in the fifth century BC.
The other half of this calendrical conundrum was, of course, the strictly solar Julian calendar of the Romans. The councils of Arles (AD 314) and Nicea (325) both affirmed the practice of celebrating Jesus’ resurrection on a Sunday, and therefore settled the Quartodeciman controversy. But the question of the precise date of Passover from year to year on the Julian calendar, and therefore of the correct Sunday for the celebration of the resurrection, was more difficult and hence longer in its resolution. This was especially the case in those regions where Christianity had far outgrown the social and geographical bounds of its origins in Judaism—particularly in the western Mediterranean, where some Christian congregations were hundreds of miles from the nearest synagogue.
It is no wonder, then, that a variety of Paschal calendars was developed by Christians during those first several centuries. It has been estimated that during the late ancient and medieval periods several hundred paschal calendars were published in books and annals.[1] By contrast, the complete collection of Easter calendars inscribed on stone and wood surviving from the entirety of Christian history numbers less than a dozen items scattered across Europe and Africa. This begs the question of the particular history of each of these stones and the content of their inscriptions. It also begs the question of the political, social, and economic conditions of the occasions and locations in which they were constructed.
This paper reflects the initial efforts of this writer to understand this small piece of the history of paschal calendars. For the purposes of this short presentation the primary emphasis has been placed on the content of the inscriptions, although much more can be said about the wider contextual matters. The inscriptions themselves have been separated into three historical categories: The first category consists of the stones surviving from the late ancient era, approximately AD 200-550. The second category consists of the meridiane created in several Italian churches from the late fifteenth through early eighteenth centuries. The third category consists of the ecclesiastical calendar discs attached to astronomical clocks in church buildings during the fourteenth through sixteenth centuries, such as the beautiful example residing with us here at Rostock. While a uniformity of material or perspective is not expected between the variety of places and times represented by these categories of inscription, it is nonetheless notable that they possess some continuity of information as their authors sought to document what they perceived as the most important event in human history. This and other factors lead this writer to conclude that these stones of Easter represent some significant high points in the history of Christian development of the computus and therefore of public celebration of the resurrection of Christ.
I. Ancient Stones of Easter: Documenting the Divine
A. Ostracon #4554
While the writings of perhaps a dozen or more authors of the first several centuries of the Christian era bear witness to the efforts of Christians to properly schedule their annual celebration of Jesus’ resurrection from the dead, that witness is likewise borne by only three stone inscriptions of the same period. The first of these hardly qualifies as a paschal calendar at all, yet its fragmentary information testifies nonetheless to the existence of early paschal calendars among Christians (whether on stone or paper), and especially to debates among Christians over the proper date of the Easter feast.
Nothing more than a chip of ancient limestone, Ostracon #4554 at the Coptic Museum in Cairo offers evidence of the widespread popularity of Quartodecimanism. From the Church History of Eusebius of Caesarea (AD 263-339), we learn that in the late second century it became the practice of Christians in the province of Asia (modern western Turkey) to celebrate both the death and resurrection of Christ on the “fourteenth day of the moon” (eve of the fourteenth day), thereby remaining faithful to the date of Jesus’ crucifixion on the fourteenth day of Nisan (Passover).
From Eusebius we learn that this practice led to a lengthy period of rancorous debate which was not quickly resolved, since it was the predominant practice of Christians elsewhere to celebrate Jesus’ resurrection on the Sunday after Passover.[2] A relatively final decision on the matter was made at the Council of Arles in AD 314 and reaffirmed at Nicea in 325[3], asserting that the resurrection of Christ should be celebrated only on a Sunday, although some Christians in Asia continued their practice for another century.
The ostracon at Cairo, however, is evidence that Quartodecimanism may well have had many followers on the south shore of the Mediterranean as well. The recto of the stone contains eight lines which feature repeated use of abbreviated versions of the Greek words μήν (meaning both “moon” and “month”), δέκα (“ten”), and τέσσαρες (“four”), referring to the fourteenth day of the moon, or Passover. The verso of the stone, on the other hand, contains a series of Egyptian calendar dates for the full moon following the spring equinox. The last five of these match the dates of the Paschal full moon for the years AD 328-332, which are known from the annual Easter letters written by Bishop Athanasius of Alexandria (326-373). It has been therefore surmised that these lines were very possibly penned by their author in the early fourth century, although a set of only five dates “may be too few to demonstrate that the years in question are identical.”[4]
B. The Sarcophagus of Hippolytus
The second ancient stone of Easter more properly fits the given category as an Easter calendar stone. It is attributed to Hippolytus (ca. 170-235), and is inscribed on the sides of his sarcophagus, which is located at the Vatican Museum in Rome. As bishop of Portus (near Rome) in the early third century—before there was a universally recognized method for calculating the dates for Easter—he was responsible for the proclamation and dissemination of this vital information. For the benefit of posterity, therefore, what was undoubtedly viewed as one of the more important accomplishments of his office is the 112-year cycle of both Easter and Passover dates which are inscribed on the two major side panels below the seated figure.[5]
On the figure’s left side is the 112-year cycle of Easter dates, corresponding to the years AD 222-333. The dates are arranged vertically in seven blocks of sixteen years each, perhaps an indication of a doubled ὀκταέτερις (octaeteris = eight-year cycle), commonly used in previous centuries by the Greeks. On the figure’s right side is an equally engaging 112-year cycle of Passover dates. Again, it is arranged vertically in seven blocks of sixteen years each, with letters of the alphabet designating the day of the week upon which Passover was to occur in a given year. Perhaps even more interesting, however, are the notations found inscribed beside several of the Passover dates which refer to historical events of Christian interest. For instance, beside the letter denoting the second year of the first cycle is an inscription stating ΓΕΝΗΣΙΣ ΧΣ (“Genesis Christos”) for the Passover date of 2 April (IV Nones April). This could be interpreted as Hippolytus’ choice of 2 April as Jesus’ birthdate, although it is just as likely that he was referring to the incarnation, meaning that Jesus was conceived in the womb of his mother Mary on 2 April and was born approximately nine months later. But it is equally important to note that the year for which the notation is apparently given is AD 223. Subtracting two complete 112-year cycles from 223—depending upon which date is chosen as the beginning of a new year—brings us to 2/1 BC.
A second notation of great interest for Christians are the words ΠΑΘΟΣ ΧΣ (pathos Christos), or “passion of Christ” beside the last date of the second sixteen-year cycle. This inscription is exactly thirty years past the first inscription, and would therefore imply Hippolytus’ belief 1) that the life of Christ was thirty years in length, and 2) that his death occurred in AD 29. In addition, these and the several other inscriptions next to Passover dates imply his belief that the dates for both Passover and Easter would repeat themselves every 112 years.[6]
While this belief is demonstrably incorrect, and while his 112-year cycle was later superseded with more accurate Paschal calendars based on the 532-year master calendar cycle, the inscription of Hippolytus nevertheless marks a significant historical moment in the development of Paschal calendars. The fact that these calendrical computations were inscribed on the funerary monument of a leading Christian bishop of the era testifies to the size and social influence of the Christian community in and around Rome in the early third century, even in spite of periodic imperial persecution. In addition, the fact that these dates were inscribed in stone for the viewing pleasure of future generations testifies to the confidence of Christians in Hippolytus’ generation that these dates were indeed correct, that they were a reliable indicator of the calendar by which Christians would celebrate what they perceived as the most important event in human history.
C. Dionysius’ Paschal Cycle in Stone
In AD 525, a monk living in Rome by the name of Dionysius Exiguus was given the assignment—apparently by the papal office—of constructing a new calendar of dates for the celebration of the resurrection of Christ. The consequent ninety-five year cycle created by Dionysius covered the years known as AD 532-626, and succeeded the previous cycle of Cyril of Alexandria which was near expiration. Dionysius is more widely known, of course, for his creation of a new dating system based upon the approximate birthdate of Christ, which in the succeeding centuries slowly became the dominant numbering system under which most of the human race now dates itself and understands its past and future.[7] While the tale of humanity’s quest to create an accurate calendar certainly has a legitimate history of its own, in which Dionysius is one of many important players, what should not be forgotten is the parallel story featured here—of the efforts of Dionysius and other Christian scholars over the centuries who endeavored to create accurate calendars of Easter.
For the purposes of this essay, moreover, what is remarkable is a curious evidence of Dionysius’ work which remains at Ravenna today in the Archiepiscopal Museum—an inscription of his Paschal cycle on a large marble slab. In a circular rosette style, it is divided into nineteen sections (resembling leaves/petals) for the nineteen years of the Metonic cycle. Flowing from the cross at the center, each set of years is designated as either “common” (having twelve lunar cycles) or “embolismic” (thirteen lunar cycles). Then beginning from the outer edge, each section lists the five years of Dionysius’ cycle which correspond to that stage of the Metonic cycle, and the date of Easter for each year. Likewise included are the annual dates of Passover and the age of the moon on Easter Sunday.
While little is known about the history of the stone itself, its very limitation to the ninety-five years of Dionysius’ cycle is a sure indication that it was inscribed shortly after his creation of the cycle itself. In addition, the impressive physical size of this calendar (approximately three-feet square) and its location at Ravenna (the western capital of Byzantium in the sixth century) are very likely indicators of its importance—that it was displayed prominently for use by ecclesiastical authorities.[8] To an equal degree, therefore, if not an even greater degree than the older inscriptions on the sarcophagus of Hippolytus, this stone makes two notable statements about Christians living in and around Ravenna three centuries later. First of all, the size and location of this inscription testifies to a large and publicly-oriented Christian population that wishes to share with the world its message of the death and resurrection of Christ. Secondly, the inscription of these calendrical details in stone again testifies to their confidence in the accuracy of the details, and therefore to their confidence in the accuracy of their own grasp of astronomical knowledge.
II. A Simple Line with a Not-so-simple Purpose: The Meridiana
No social institution of western civilization was challenged more deeply by the events and processes of the early modern era (roughly 1400-1800) than the Roman Catholic Church. The artistic and philosophical challenges of the Renaissance, the theological and organizational challenges of the Protestant Reformation, and the scientific and political challenges of the Enlightenment all combined to bring into question many of the practices and assumptions of Catholicism, and motivated it toward several reforms. One notable reform in the midst of this era was the proclamation of the Gregorian calendar in 1582. Astronomers were universally agreed for centuries on the inaccuracies of the old Julian calendar and had proposed revisions to Rome. But the popes were nevertheless reluctant to move ahead with a calendrical revision—specifically because of its effect on the annual date of Easter. Since Easter was inextricably linked to not only the date of Passover but also the vernal equinox, any calendrical revision brought into question the paschal calendars of the era.
One simple scientific instrument which was instrumental in this reform is the meridiana, or meridian line.[9] A meridiana is at its core a simple line which performs a function inside a building similar to that accomplished by a sundial outside a building. It tells time, yet not in the same way. Rather than measuring the changing angle of the sun in its daily passage across the heavens from east to west, a meridiana is a line oriented north-south to note the sun’s changing angle toward a particular location at a particular time each day. This angle changes as the Earth proceeds through its annual orbit and its inclination of nearly 23.5˚ on its axis causes the variations of light and temperature.
A few meridiana had been installed in the floors of Italian churches already before the Gregorian revision of the calendar. Most notable among these is the line at the Cathedral of San Petronio in Bologna, which had been only recently installed by Ignazio Danti (1536-1586) in 1575. Because of Danti’s success, he was soon appointed by Gregory to the calendrical commission, where he played at least a minor role. A final meridiana was installed in an Italian church in 1702, this time in Rome. Its location was in the Basilica church of Santa Maria degli Angeli, which until 1560 had been simply the ruins of the Baths of Diocletian. Nearly one and one-half centuries after its conversion into a church to honor the Christians who had been martyred by Diocletian, Pope Clement XI commissioned Francesco Bianchini (1662-1729) to build a meridiana to symbolize the victory of his predecessor Gregory’s Christian calendar over the old pagan Julian calendar.
Although the gnomon at Santa Maria degli Angeli is not as high and the line not as long as that at Bologna, Bianchini’s meridiana was nevertheless constructed with minute attention to detail.[10] One of those details—admittedly the original reason behind the construction of all meridiane but curiously omitted at Bologna and elsewhere—was the notation of the Terminus Paschae, or the calendrical limits of Easter. For most modern observers, it is necessary to read the line somewhat backward calendrically. Proceeding from the summer solstice—the far south end of the line nearest the wall where the gnomon admits the beam of sunlight—and counting up to day fifty-five, one observes the unmistakable papal seal of Clement XI. Day fifty-five from (before) the summer solstice is 25 April—the latest possible date of Easter. Following northward the increasing numbers on the line brings one backward calendrically to day ninety before the summer solstice—at 22 March, thirty-five days before 25 April and the earliest possible date of Easter. Hence, from the perspective of simple observation, the riddle of Easter had been finally solved and documented by Bianchini’s meridiana.
III. Astronomical Clocks and Calendar Discs: Uniting the Sacred and Secular
This brings us to the third and final form of the Stones of Easter—the calendar discs attached to astronomical clocks in locations north of Italy, from the late fourteenth century onward.[11] Beginning in 1383 in Lyon and stretching through 1540 in Münster, these calendar discs and the clocks to which they are attached give a visible public witness of two things: First of all, they give obvious witness of the increasing astronomical knowledge of Europeans in the late medieval to early modern period, as well as their increasing confidence in the accuracy of their calculations. Secondly, these calendar discs give witness to the desire of their creators to place their astronomical knowledge within the larger context of divine activity in human history. By doing once more what early generations of Christians had sought to do—to document the timing of the most important event in human history, the death and resurrection of Christ—they gave ultimate meaning to their astronomical calculations by placing them within the divine cosmos.
In the interest of time and in this company, I will not take the time to engage in a thorough description of each of the calendar discs and their contents. (Some of the rest of us here could certainly do that much better than I.) At the very least, I must agree wholeheartedly with Schukowski’s assertion that the astronomical clocks are an example of “medieval high tech” (“mittelalterliches Hightech”[12]) due to both the exacting technology of their constituent parts and the several realms of knowledge brought together in their display. What I will do, however, is to take a moment to describe what I believe is a significant difference in the information presented on these calendar discs over against their ancient predecessor at Ravenna.
One notable difference between the calendrical information found on the calendar discs, such as the one residing with us here at Rostock, and their late ancient predecessor at Ravenna containing the calculations made by Dionysius Exiguus in the sixth century, is their orientation with respect to the Metonic cycle. The difference is twofold: First of all, the inscriptions at the outer edge of each of the “leaves” of the calendar stone at Ravenna show that the first year of Dionysius’ paschal cycle is linked to the seventeenth year of a previously-existing Metonic cycle. Consequently, the fourth year of Dionysius’ paschal cycle is linked to the first year of the Metonic cycle.[13] By contrast, on the calendar discs attached to the astronomical clocks the first year of each Metonic cycle has been synchronized with the first year of a paschal cycle. For instance, as we see on the calendar disc here in Rostock, our current year of 2012 is listed as year eighteen of the Metonic cycle. By simple calculation we will discover that 2012 is exactly 1,463 years after AD 549, which is the eighteenth year of the first cycle on Dionysius’ paschal calendar. 1,463 years is exactly 77 Metonic cycles. But on Dionysius’ table, AD 549 is listed as year fifteen of the Metonic cycle.
So the question must be asked: Why the difference? In other words, when was this change made, and why? First, a point of reference worthy of note is a further inscription on the marble slab just outside the leaf representing the ninth year of the paschal cycle—“DIVISIOCYC·LI·II” (“division of cycle 51, part II”). This means that Dionysius (or at least the author of the stone inscriptions) understood that his paschal cycle began with the fifty-first Metonic cycle since its origin, and that it was a combination of an eight-year cycle with an eleven-year cycle. Interestingly, if one subtracts exactly 51 Metonic cycles (969 years) from AD 535—the first date in Dionysius’ paschal table which is matched with the first year of a Metonic cycle—the result is 435 BC. This is the period when the Greek astronomer Meton and his associates in Athens designed the cycle which still bears his name.[14] Using 435 BC as a [corrected] baseline for counting Metonic cycles carries with it the implication that the sources used by Dionysius for his calculations pointed in this direction. Unfortunately, Dionysius did not specify his sources in this matter.
When was the change made, and why? While additional research is necessary for a final conclusion, the following assertions can be made: First of all, it is clear that Bede was still utilizing the Dionysian orientation two hundred years later when he wrote his De temporum ratione. His “532-Year Paschal Table” designated AD 532 and every other year at the beginning of a nineteen-year paschal cycle (AD 551, 570, 589, etc.) as the seventeenth year of the lunar (Metonic) cycle.[15]
Secondly, it is likewise clear that by the end of the eighth century in the realms of Charlemagne the change in orientation had already been made. Alcuin’s answer to the emperor and his advisors on a question concerning the observed age of the Easter full moon (in March) and its effect on the possible date of Easter includes the observation that AD 799 was the second year of the nineteen-year lunar cycle. Again, simple math tells us that AD 799 is 266 years after 533, or exactly fourteen Metonic cycles. AD 533 is shown on the Dionysian table as the second year of the paschal cycle, but the eighteenth year of the Metonic cycle. The assertion by Alcuin that AD 799 is simply the second year of the lunar cycle, without further clarification, is therefore an indication that the synchronization of the Metonic cycle with the paschal cycle had already been accomplished.[16]
While the exact date of the synchronization is unclear, it is certainly plausible that the adjustment was made as part of the Carolingian calendar reform only recently enacted.[17] The reasons behind the synchronization are also unclear, although it is equally plausible that Alcuin followed the example of Dionysius in suggesting a further Christian orientation to the calendar: In addition to constructing a new paschal cycle, Dionysius had asserted a (very possibly) new calendrical orientation around the concept of Anno Domini.[18] Similarly, it is equally plausible that Alcuin saw no further need to retain the pre-Christian Greek numbering for the Metonic cycle, and therefore synchronized it with the paschal cycle so that the year of the incarnation and birth of Christ was the first year of the cycle rather than the seventeenth.
A second difference between the paschal calendar of Dionysius and those attached to the astronomical clocks is the occurrence of the embolismic years within each nineteen-year cycle. As we can see once more on the calendar disc here at Rostock, 2014 will be an embolismic year, as evidenced by the fact that the date of Easter jumps forward twenty days from 31 March to 20 April. In addition, the Golden Number tells us that 2014 is the beginning of a Metonic Cycle. Once more, simple calculation tells us that 2014 is 1,482 years past AD 532, or exactly 78 Metonic cycles. AD 532 is the first year of Dionysius’ paschal cycle, and as we see on his chart it was not an embolismic year but a common year. By further observation we see that nearly 1,500 years ago when Dionysius made his calculations the Metonic pattern was to include embolisms in years 3, 6, 8, 11, 14, 17, and 19. By contrast, the modern pattern, as shown by the calendar discs on the astronomical clocks, includes embolisms in years 1, 4, 6, 9, 12, 15, and 17.
So again the question must be asked: Whence the change, and why? In this case, the answer is found in the consequences of the adoption of the Gregorian calendar reform in 1582. Close observation of the dates of Easter in the Metonic cycle already in progress at the date of the reform (AD 1577-1595) shows how adjustments were made: AD 1583—the first year affected by the reform—was the seventh year of the Metonic cycle and therefore would have been a common year according to the old pattern. It remained a common year in the new pattern, but since ten days were eliminated from October 1582, the date of Easter regressed by only five days rather than the usual eight or fifteen. The next year, 1584, contains an even more noticeable difference. Under the old pattern, as the eighth year of the Metonic cycle, it would have been an embolismic year. But with the elimination of the ten days one and one-half years previous there was no need for the embolism. So instead of vaulting ahead by twenty days, the date of Easter simply regressed another nine days and the year was common. In fact, observation of the Metonic cycle for 1577-1595 shows that only six embolisms were required rather than the usual seven—in years 3, 6, 9, 12, 14, and 17 (1579, 1582, 1585, 1588, 1590, and 1593). But it also required that the next Metonic cycle begin with an embolismic year (1596) in order to keep the date of Easter within the limits already established.
This also explains a major reason why Greek Orthodox officials and theologians rejected the Gregorian reform when informed by representatives from Rome, and why they have been very slow even to implement elements of it ever since. Although Orthodox leaders were equally aware of the faults of the Julian calendar, they were even more reluctant than their western counterparts to make any amendments to a practice that had endured more than a thousand years.
Clearly, further research into these questions, as well as the contextual matters surrounding the particular histories of each of these stones of Easter, will yield additional insights into these significant moments in the historical development of both western calendars in general and paschal cycles in particular. While my research thus far has focused on matters that may seem rather minute and remote from the concerns of most, these matters were certainly not remote from the concerns of earlier generations of Christians who sought to document and celebrate the most important event in human history.
Notes
[1] Evelyn Edson, “World Maps and Easter Tables: Medieval Maps in Context,” Imago Mundi 48 (1996): 25; http://www.jstor.org/stable/1151259.
[2] Church History V, 23-25, in NPNF 2, I, 241ff.
[3] NPNF 2, XIV, 54. The modern reader will no doubt note what appears to be an anti-Jewish tone in the words of Constantine—words which have sometimes come back to haunt Christians more recently. Without trying to defend Constantine, we should note that this is not only a reflection of Christianity’s rise to power in the late Roman world, but also of the bitter memory of many Christians who were ousted from Jewish communities. For more on the Quartodecimans, including some of their own statements, see Easter in the Early Church: An Anthology of Jewish and Early Christian Texts (Raniero Cantalamessa, ed. Collegeville, MN: Liturgical Press, 1993), 33-37, 46-50.
[4] S. Kent Brown, “An Easter on Limestone,” Acts of the Fifth International Congress of Coptic Studies; Washington, 12-15 August 1992 (1992): 89.
[5] For more on the history of the sarcophagus itself, see Allen Brent, Hippolytus and the Roman Church in the Third Century: Communities in Tension before the Emergence of a Monarch-Bishop (Leiden: E. J. Brill, 1995), 7-50.
[6] PG X, 875ff. Unfortunately, modern calendar converters show that Hippolytus’ faith in the 112-year cycle was unfounded, as the dates of Passover do not repeat themselves exactly after this interval. In addition, 2 April, 2 BC corresponded roughly to 28 Nisan, not the Passover date of 14 Nisan. Similarly, 2 April, 1 BC corresponded to 9 Nisan. Moreover, the most likely date of Jesus’ crucifixion is 3 April AD 33 (14 Nisan 3793).
[7] For a review of the calendrical work of Dionysius Exiguus and the several debates surrounding its construction, intent, and historical usage, see Steven L. Ware, When was Jesus Really Born: Early Christianity, the Calendar, and the Life of Jesus (St. Louis: Concordia, forthcoming), chapter five. See also Georges Declercq, Anno Domini: The Origins of the Christian Era (Brussels: Brepols, 2000); Alden A. Mosshammer, The Easter Computus and the Origins of the Christian Era (Oxford: Oxford University Press, 2008). The chronological works of Dionysius are found in PL LXVII.
[8] Little information on the history of the stone is given, except that the slab came from a quarry on the island of Proconnesus in the Sea of Marmara, near the coast of modern Turkey. One travel blog described this stone as “striking but indecipherable” (http://www.travel-wonders.com/2009/07/touring-mosaic-city-ravenna-italy-part_10.html). It is certainly striking, but far from indecipherable, as many of this writer’s students will attest.
[9] For more on the history and use of the meridiane, see Ware, chapter six. For more on the astronomical and mathematical theory behind their construction, see also J. L. Heilbron, The Sun in the Church: Cathedrals as Solar Observatories. Cambridge: Harvard University Press, 1999.
[10] Heilbron, 152ff.
[11] It should be admitted here that all of the calendar discs attached to astronomical clocks are actually made wood, not stone. I have nevertheless placed them in the same category as the other stones because they were made for the same purpose and therefore make the same kind of public statement: While the same categories of information can be found in numerous books and annals throughout the medieval and early modern periods, the calendar discs were placed deliberately in very public locations so that their information was available to a much wider spectrum of humanity than the few monks or scientists who would take the time to read the annals.
[12] Manfred Schukowski, Wunderuhren: Astronomische Uhren in Kirchen der Hansezeit (Schwerin: Thomas Helms, 2006), 9-10. In addition to thorough descriptions of each of the clocks in the Hanseatic cities, also included are several helpful appendices (125ff) giving historical and constructive details of all known astronomical clocks across Europe.
[13] For the paschal table of Dionysius Exiguus, see PL LXVII, 493ff; also found at http://hbar.phys.msu.ru /gorm/chrono/paschata.htm.
[14] Borst (Die karolingische Kalenderreform [Hannover: Hahnsche, 1998], 687) and others have asserted 432 BC as the beginning date for use of the Metonic cycle, although without lengthy explanation.
[15] Faith Wallis, Bede: The Reckoning of Time (Liverpool: Liverpool University Press, 1999), 392-404. Bede also affirms the continued use of Dionysius’ pattern for common and embolismic years (122-123).
[16] Kerstin Springsfeld, Alcuin’s Einfluß auf die Komputistik in der Zeit Karls des Großen (Stuttgart: Franz Steiner, 2002), 168-169.
[17] Borst (231ff) contends that the reform was begun with the work of Alcuin at Lorsch in AD 789. See also Monumenta Germaniae Historica (Hannover: MGH, 1883), I, 60; http://www.mgh.de/bibliothek.htm.
[18] Dionysii Exigui, “Epistolae Duae de Ratione Paschae,” PL (Montrouge: Parisiorum, 1848), LXVII, 19ff.