Meton and the calendaric cycle (1)

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The first scientific and religious importations from Babylonia to Greece are assigned to a period when the commercial cities of Ionia threw open their gates to Asiatic influences. It is more important to collect the traces of these Babylonian infiltrations after the Persian wars when Greek thought had achieved its autonomy. Certain facts indicate that the relations, direct or indirect, between the centres of Babylonian learning and of Greek culture were never at any time entirely broken off. Since from early times the Babylonian calendar had the tendency to co-ordinate the lunar calendar more or less with the seasons of the solar year, the mathemization of astronomy in the fifth century BCE is reflected in a definite intercalation cycle, usually called the Metonic cycle appear simultaneously in Babylon and Greece. This quite accurate and convenient cycle intercalates seven additional months in nineteen lunar years. Meton, who in 432 BCE introduced the calendar, replaced the ancient cycle of eight years. The cycle of eight years is proved to have been in use at Babylonia, by documents of the sixth century and the 19 year cycle is attested in inscriptions of the fourth century, and this latter may well be much older.

This calendar in combinations with the continued counting of the regnal years of Seleucus I, beginning at 312 BCE, constitutes one of the greatest advances in practical chronology. Here we have for the first time a precise era in which dates can be accurately established according to simple computational rules. It seems difficult to believe that Meton was not prompted by the example which Babylonia set him. This is the more probable because he appears to have had some acquaintance with astrology, if one believes that at the moment of the departure of the fleet for Sicily, his science revealed to him the disaster which awaited that expedition. An aspect of the later history of the nineteen-year cycle is contained in the history of Easter cycles, where a simple and practical solution of one problem was contaminated by additional conditionals (e.g. Easter limits), which deprived the original solution of its main value, simplicity. Indeed, that simplicity was the element that recommended the nineteen-year cycle to the Babylonian astronomers is demonstrated by the fact that the mathematical astronomical texts of the whole Seleucid-Parthian period maintained the use of the nineteen-year cycle as the chronological skeleton of their computations in spite of the fact that they used, for their lunar epherides themselves, relations of higher accuracy than those reflected in the calendaric cycle.

Bibliography

Amar Annus

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