Extispicy, Liver Divination

Extispicy began with a question, not an animal. A client, very often a king weighing a military campaign, a royal marriage or an appointment, formulated a precise yes-or-no question and had it addressed formally to the sun god Shamash and the storm god Adad, the two deities credited with governing truthful divination. A sheep was then sacrificed, and the baru priest opened the carcass to examine its internal organs, above all the liver, which Mesopotamian thought treated as the seat of the animal's life and therefore as a surface the gods had, in effect, just written their answer onto. The lungs, coils of intestine and the gall bladder were read as well, but the liver, with its distinctive lobes, gall bladder duct and a small triangular protrusion called the "finger," carried the weight of the reading and gave the discipline its ancient name, barutu, the craft of the baru.

The interpretation was not improvised. Generations of recorded readings had been compiled into omen compendia, above all the massive series conventionally called Baru, which paired specific liver features with specific outcomes in a fixed, citable body of precedent, closer in structure to a legal casebook than to free intuition. Clay models of a sheep's liver, some inscribed with sample omens and some left blank for teaching, survive from sites including Mari and are read by Assyriologists as training aids for apprentice diviners learning to recognise and name each anatomical feature before they were trusted to read a real one.

Extispicy was not a fringe practice consulted only in private anxiety, it was built into how Mesopotamian states actually made decisions. Royal archives, particularly from the Old Babylonian kingdom of Mari and from the Neo-Assyrian court, preserve extensive correspondence in which baru priests report their readings directly to the king before military campaigns, building projects and diplomatic decisions, and a negative or ambiguous liver could delay or cancel action a king had otherwise already resolved on. The baru priesthood constituted a recognised professional class with its own training, its own textual canon and, at the royal level, direct access to political power that few other kinds of priest possessed, since a king who ignored an unfavourable extispicy risked being seen by his own court as defying the gods' explicit answer rather than merely bad advice.

The practice also had to survive its own uncertainty. Because a single reading could be judged flawed, ambiguous, or contradicted by a second sacrifice, Mesopotamian diviners developed formal procedures for repeating an extispicy and for weighing conflicting results, a level of internal methodological self-scrutiny that modern historians of science and divination alike have found notable. Extispicy's prestige and its heavy documentation, resting on the sheer bulk of the omen literature it generated, made it the benchmark against which other Mesopotamian divinatory techniques, including astrology and the reading of unusual births, were measured for authority and reliability.