CHAPTER NINE THE DATE OF THE CRUCIFIXION: THE MISUSE OF CALENDARS AND ASTRONOMY TO DETERMINE THE CHRONOLOGY OF THE PASSION
The simplicity, clarity and convenience of having a single system of chronology for world history is something which is tacitly confessed by the general and long-standing acceptance of such a system, though its benefits are more often taken for granted than explicitly recognised. It is true that, from one point of view, the introduction of our present Christian system of chronology by Oionysius Exiguus in the sixth century A.O., and its subsequent adoption world-wide, was only a natural sequel to the conversion of the Roman Empire. Nevertheless, the system has served mankind well, and still does; so much so, that even those who do not acknowledge the central place of Jesus Christ in world history remain glad to use it (sometimes under an adapted nomenclature) for ordinary purposes; and even the discovery that Oionysius placed the transition between B.C. and A.O. a few years too late has simply been accepted as a fact, without any serious attempt being made to modify (still less to supersede) his system.
CHRONOLOGIES AND CALENDARS IN THE ANCIENT WORLD
The very different situation that obtained at the beginning of the Christian era is lucidly outlined in the opening chapters of Professor Jack Finegan's Handbook of Biblical Chronology (Princeton: The University Press, 1964). A variety of eras then served as reference-points for chronology. Among others, there were the Greek Olympiads (four-year periods, dating from an early celebration of the Olympic Games in what we call 776 B.C.), the era of the foundation of the city of Rome (which the learned Roman historian Varro had placed in the year 753 B.C.), the Seleucid era (dating from the victory of Seleucus I, the founder of the Greek dynasty in Syria, at the Battle of Gaza, 312 B.C.) and the era of the creation of the world (which the rabbinical chronicle Seder Olam Rabbah fixed at about 3761 B.C.). 1 Often, however, years were identified in a different manner, from the accession of a
1 Most of the Jewish and early Christian chronologies discussed in the previous chapter agree with Seder Olarn Rabbah in beginning from the creation, though they disagree a good deal as to when the creation should be reckoned to have taken place. THE DATE OF THE CRUCIFIXION 277 particular ruler or official, and it is in this way that the beginning of the ministry of John the Baptist is dated in Luke 3: If. In. either case, a modem student needs to determine how the years are being counted, i.e. at what season does the new year begin? and does the numbering start from the year in which the great event occurred or the ruler took office, or from the first complete year after it? And then again, he needs to investigate how the year itself is being reckoned, and what calendar is being used. Is it a lunar calendar of 354 days, or a solar calendar of something around 365 days? and is it an exact calendar, fixed by careful astronomical calculation, or an approximate calendar, intended for practical utility rather than scientific precision? Only when all these considerations have been taken into account can one begin to transpose the chronological information given by ancient writings into terms of our own chronology, and one must not be surprised if the conclusions that are reached are at best probable rather than certain, especially when one is trying to fix the month or the day of a particular occurrence, as well as the year. The development of a scientifically exact calendar occurred in different nations at different periods, according to the rate at which the study of astronomy advanced there, and gained acceptance for its findings. In the lands of the Bible, Babylon and Egypt were the countries where astronomy was earliest studied, but Greece had caught up by the fifth century B.C., when the Greek astronomer Meton devised or adopted the 19-year cycle (afterwards refined by Callippus and Hipparchus) for reconciling the lunar year to the solar; though in practice Greece continued to use a less accurate 8-year cycle. Since twelve lunar months amount to only about 354 1/J days, the lunar calendar has to be adjusted periodically to the solar year of about 365 1/4 days, by the addition of a thirteenth month, so as to keep it in line with the seasons. Originally this was done irregularly, whenever it was seen to be necessary from the lateness of the seasons, but the 19-year cycle (adopted also by the Babylonians in about the fifth century B.C.) made it possible to add the thirteenth month at fixed intervals, and to settle in advance the leap years in which it needed to be added. Babylon and Greece both used a lunar calendar, adjusted in the way described, and lunar calendars also existed in Egypt. There, however, an important solar (or stellar) calendar also existed, governed by the heliacal rising of the dog-star, i.e. its rising in proximity to the rising sun. Since Egypt is a flat country with a true horizon, the heliacal rising of the brightest of the stars was easily seen, and from very early times Egyptian astronomers noted that it happened about every 365 days. The 365-day calendar based on this fact was not, of course, absolutely exact, and in 238 B.C. one of the Greek kings of Egypt, Ptolemy Euergetes I, issued his Decree of Canopus, proposing the addition of a day to every fourth year, so as to rectify the