Divination & the Reading of Omens
The gods wrote the future into a sheep's liver and the night sky — and trained scholars learned to read it.
Also: divination · omens · extispicy · baru · bārû · liver divination · Enuma Anu Enlil · celestial omens · haruspicy
Mesopotamians believed the gods wrote their intentions into the world as signs, which a trained scholar could read. The diviner (baru) inspected the liver and entrails of a sacrificed sheep (extispicy); other experts watched the sky, monstrous births, the behavior of animals, oil on water, or smoke. The results were compiled into enormous reference series of conditional omens — 'if such-and-such appears, then such-and-such will happen.' This was a genuine intellectual discipline: systematic, cumulative, and empirical in its own way, applied above all to guide the king. Divination was Mesopotamia's chief science of the future, and the root of its astronomy.
In short
The learned science of reading the gods' intentions in signs — the entrails of sacrificial animals (extispicy), celestial events, births, and chance phenomena — codified in vast 'if… then…' omen series.
Where it’s found
The extispicy (bārûtu) and celestial (Enūma Anu Enlil) omen series (akkadian-pending; Koch, Mesopotamian Divination Texts); divinatory motifs in the Sumerian corpus (in corpus)
How the idea developed across Sumer, Babylon & Assyria
Extispicy (liver/entrail divination) is central and old; celestial divination is codified in the great series Enūma Anu Enlil. Crucially, the systematic observation behind celestial omens grows into genuine mathematical astronomy in the later first millennium — the documented seedbed of Greek astronomy/astrology (see mes-celestial-science). Omen apodoses are not predictions of fact; treat them as a divinatory system.