Hepatoscopy, or divination through the liver, belongs therefore to the primitive period when that organ summed up all vitality and was regarded as the seat of all the emotions and affections - the higher as well as the lower - and also as the seat of intellectual functions.
The theory underlying hepatoscopy therefore consists of these two factors: the belief (I) that the liver is the seat of life, or, to put it more succinctly, what was currently regarded as the soul of the animal; and (2) that the liver of the sacrificial animal, by virtue of its acceptance on the part of the god, took on the same character as the soul of the god to whom it was offered.
Hepatoscopy in the Euphrates valley can be traced back to the 3rd millennium before our era, which may be taken as sufficient evidence for its survival from the period of primitive culture, while the supreme importance attached to signs read on the livers of sacrificial animals - usually a sheep - follows from the care with which omens derived from such inspection on occasions of historical significance were preserved as guides to later generations of priests.
The inspection of the liver for purposes of divination led to the study of the anatomy of the liver, and there are indeed good reasons for believing that hepatoscopy represents the startingpoint for the study of animal anatomy in general.
Whether the division of the lobus dexter into two divisions - (i) lobus dexter proper and (2) lobus quadratus, as in modern anatomical nomenclature - was also assumed in Babylonian hepatoscopy, is not certain, but the groove separating the right lobe into two sections - the fossa venae umbilicalis - was recognized and distinguished by the designation of "river of the liver."
The former of these two appendixes plays an especially important part in hepatoscopy, and, according to its shape and peculiarities, furnishes a good or bad omen.
It is well known that the Romans borrowed their methods of hepatoscopy from the Etruscans, and, apart from the direct evidence for this in Latin writings, we have, in the case of the bronze model of a liver found near Piacenza in 1877, and of Etruscan origin, the unmistakable proof that among the Etruscans the examination of the liver was the basis of animal divination.
As for the Greeks, it is still an open question whether they perfected their method of hepatoscopy under Etruscan influence or through the Babylonians.
In any case, since the Eastern origin of the Etruscans is now generally admitted, we may temporarily, at least, accept the conclusion that hepatoscopy as a method of divination owes its survival in advanced forms of culture to the elaborate system devised in the course of centuries by the Babylonian priests, and to the influence, direct and indirect, exerted by this system in the ancient world.
But for this system hepatoscopy, the theoretic basis of which as above set forth falls within the sphere of ideas that belong to primitive culture, would have passed away as higher stages of civilization were reached; and as a matter of fact it plays no part in the Egyptian culture or in the civilization of India, while among the Hebrews only faint traces of the primitive idea of the liver as the seat of the soul are to be met with in the Old Testament, among which an allusion in the indirect form of a protest against the use of the sacrificial animal for purposes of divination in the ordinance (Exodus xxix.
4, 10, 15, &c.) to burn the processus pyramidalis of the liver, which played a particularly significant role in hepatoscopy, calls for special mention.
In modern times hepatoscopy still survives among primitive peoples in Borneo, Burma, Uganda, &c.