ideal year

Definition

Ideal year is David Brown's scholarly term for the conceptual 12-month 30-day-month year totalling 360 days, treated in his account as the foundational ideal-period scheme of Mesopotamian celestial divination — the theological-arithmetical substrate against which observed phenomena were judged ominous when they deviated ("ina la minātišu," "not according to its count"). The ideal year stands at the head of a family that includes Brown's ideal month, ideal Venus scheme, ideal lunar visibility, and ideal solar movement.

In Tradition

Brown argues, with Hunger and Pingree concurring on the calendrical fact, that the 360-day administrative year documented in third-millennium BCE Sumerian texts (per Englund 1988) carried into the divinatory tradition through EAE: when observed phenomena correspond with the ideal the gods are pleased; divergence bodes ill. The exponents of MUL.APIN, in Brown's reading, knew the real year was not 360 days but kept the idealised value for its divinatory utility.

In Practice

For the reader of the EAE corpus, MUL.APIN, the Diviner's Manual, BM 17175+17284, and i.NAM.giš.ḫur.an.ki.a, the ideal year is the implicit divinatory yardstick against which any departure of an observed celestial event is read as ominous. Brown anchors the scheme in BM 17175+17284 (an Old Babylonian text from Sippar or Tell ed-Der, published in Hunger-Pingree *MUL.APIN* pp. 163-4) which presupposes the 12-month year, the 2:1 ratio of longest to shortest night, and a spring equinox on month XII 15 — the OB convention later shifted to Nisannu 15. Brown reads the ideal year as the generative root of his ideal-period-scheme family: the ideal month treats day 15 as the day the Moon is visible all night, the ideal Venus scheme assigns 8m5d-visibility + 3m7d-invisibility per phase, the ideal lunar-visibility scheme gives night-fractions n/15 across days 1-14. The scheme is the divinatory engine of the EAE Paradigm: every omen-protasis that names a date or duration uses ideal-year reckoning as baseline.

Historical Origin

Attested from the Old Babylonian period (BM 17175+17284, OB coefficient lists, Atrahasis II.13 + IV; third-millennium BCE Sumerian administrative texts per Englund 1988) through the canonical MUL.APIN (~1000 BCE composition) into the Late-Assyrian EAE tradition. Modern critical treatments: David Brown, *Mesopotamian Planetary Astronomy-Astrology* (Styx, Cuneiform Monographs 18, 2000), §3.1.2 pp. 123-128 and Appendix 1 §§8, 11 pp. 259-260; cross-attestation in EAE 14, i.NAM.giš.ḫur.an.ki.a, the Diviner's Manual, and the OB coefficient-list tradition.

Further Reading

• David Brown, Mesopotamian Planetary Astronomy-Astrology
• Hermann Hunger & John Steele, The Babylonian Astronomical Compendium MUL.APIN