Calendars and Years by John M. Steele;

Author:John M. Steele;
Language: eng
Format: epub
ISBN: 9781782974932
Publisher: Casemate Publishers & Book Distributors, LLC
Published: 2013-08-27T00:00:00+00:00

The 360-Day Year in Mesopotamia

Lis Brack-Bernsen

The Cultic or Civil Calendar and the “Administrative Calendar”

From ancient Mesopotamia we know two different “calendars”: the cultic or civil calendar and the “administrative calendar”.1 In both calendars, the year was the largest unit. In the cultic calendar, the year was divided into lunar months of 29 or 30 days. In the administrative calendar each month was put equal to 30 days. As we shall see, the administrative calendar was only used in the context of making calculations and never for dating. This latter use was taken care of by the cultic calendar which was defined by the solar year and by lunar phases: the first day of a new month began on the evening when the new crescent became visible for the first time after conjunction. First visibility takes place either 29 or 30 days after the previous first visibility. Since the sequence of 29- and 30-day months is highly irregular the cultic calendar was troublesome to handle. The mean value of the synodic month (the time between two consecutive conjunctions or oppositions) is approximately 29.53 days, so that 12 lunar months equals about 354.37 days, some 10.88 days shorter than the solar year. Therefore, on the average, an intercalated month was necessary every three years or so in order to keep the months in tune with the seasons.

This paper shall present textual evidence for the claim that both systems of time measurements were used simultaneously from the early dynastic time (ca. 2600 BC) until around 1000 BC when the astronomical-astrological compendium MUL.APIN was composed. Prior to the early dynastic period there is insufficient evidence to say for certain whether the lunar calendar was used; the protoliterate texts (from ca. 3200 BC) have not been understood sufficiently—one can only speculate, that some signs in Uruk III texts may refer to the kind of cultic lunar month known from later periods. However, the number systems in these very early texts are sufficiently well understood to enable us to understand the calculations they contain and to establish that rations in bureaucratic texts were calculated of the basis of the administrative year. The paper shall also clarify how (i.e., for what or in which way) the two calendars were used: the cultic calendar for dating and the administrative one for centralized bookkeeping and later also for astronomy. For example, in MUL.APIN, a canonical astronomical /astrological text perhaps dating from around 1000 BC, we find astronomical schemes in which the ideal year of 360 days is used, together with indications of how to adjust schematic values according to observations.

I start with Ur III texts, which are understood profoundly, and then go backwards in time to the earlier texts. The knowledge gained from the Ur III texts makes it is easier to understand and explain older texts. For textual evidence from earliest times until the end of Ur III times (2000 BC), I rely mostly on R. K. Englund’s investigations in “Administrative Timekeeping in Ancient Mesopotamia” (1988), a careful and systematic analysis of all available texts of interest together with many useful references.

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