To read the signs of the heavens was therefore to understand the meaning of occurrences on earth, and with this accomplished it was also possible to foretell what events were portended by the position and relationship to one another of sun, moon, planets and certain stars. Myths that symbolized changes in season or occurrences in nature were projected on the heavens, which were mapped out to correspond to the divisions of the earth. All the gods, great and small, had their places assigned to them in the heavens, and facts, including such as fell within the domain of political history, were interpreted in terms of astral theology. So completely did this system in the course of time sway men's minds that the cult, from being an expression of animistic beliefs, took on the colour derived from the "astral" interpretation of occurrences and doctrines. It left its trace in incantations, omens and hymns, and it gave birth to astronomy, which was assiduously cultivated because a knowledge of the heavens was the very foundation of the system of belief unfolded by the priests of Babylonia and Assyria. "Chaldaean wisdom" became in the classical world the synonym of this science, which in its character was so essentially religious.
The persistent prominence which astrology (q.v.) continued to enjoy down to the border line of the scientific movement of our own days, and which is directly traceable to the divination methods perfected in the Euphrates valley, is a tribute to the scope and influence attained by the astral theology of the Babylonian and Assyrian priests.
As an illustration of the manner in which the doctrines of the religion were made to conform to the all-pervading astral theory, it will be sufficient to refer to the modification undergone in this process of the view developed in a very early period which apportioned the control of the universe among the three gods Anu, Bel and Ea. Disassociating these gods from all local connexions, Anu became the power presiding over the heavens, to Bel was assigned the earth and the atmosphere immediately above it, while Ea ruled over the deep. With the transfer of all the gods to the heavens, and under the influence of the doctrine of the correspondence between the heavens and the earth, Anu, Bel and Ea became the three "ways" (as they are called) on the heavens. The "ways" appear in this instance to have been the designation of the ecliptic circle, which was divided into three sections or zones - a northern, a middle and a southern zone, Anu being assigned to the first, Bel to the second, and Ea to the third zone.
The astral theology of the Babylonian-Assyrian religion, while thus bearing the ear-marks of a system devised by the priests, succeeded in assimilating the beliefs which represented the earlier attempts to systematize the more popular aspects of the religion, and in this way a unification of diverse elements was secured that led to interpreting the contents and the form of the religion in terms of the astral-theological system.
The most noteworthy outcome of this system in the realm of religious practice was, as already intimated, the growth of an elaborate and complicated method of divining the future by the observation of the phenomena in the heavens. It is significant that in the royal collection of cuneiform literature made by King Assur-bani-pal of Assyria (668-626 B.C.) and deposited in his palace at Nineveh, the omen collections connected with the astral theology of Babylonia and Assyria form the largest class. There are also indications that the extensive texts dealing with divination through the liver of sacrificial animals, which represents a more popular origin than divination through the observations of the heavens, based as it is on the primitive view which regarded the liver as the seat of life and of the soul, were brought into connexion with astral divination. Less influenced by the astral-theological system are the old incantation texts which were gathered together into series. In these series we can trace the attempt to gather the incantation formulae and prayers produced in different centres, and to make them conform to the tendency to centralize the cult in the worship of Marduk and his consort in the south, and of Assur and Ishtar in the north.
Incantations originally addressed to Ea of Eridu, as the god of the watery element, and to Nusku, as the god of fire, were transferred to Marduk. This was done by making Ea confer on Marduk as his son the powers of the father, and by making Nusku a messenger between Ea and Marduk. At the same time, since the invoking of the divine powers was the essential element in the incantations, in order to make the magic formulae as effective as possible, a large number of the old local deities are introduced to add their power to the chief ones; and it is here that the astral system comes into play through the introduction of names of stars, as well as through assigning attributes to the gods which clearly reflect the conception that they have their seats in the heavens. The incantations pass over naturally into hymns and prayers. The connexion between the two is illustrated by the application of the term shiptu, "incantation," to the direct appeals to the gods, as well as by the introduction, on the one hand, of genuine prayers into the incantations and by the addition, on the other hand, of incantations to prayers and hymns, pure and simple.
In another division of the religious literature of Babylonia which is largely represented in Assur-bani-pal's collection - the myths and legends - tales which originally symbolized the change of seasons, or in which historical occurrences are overcast with more or less copious admixture of legend and myth, were transferred to the heavens, and so it happens that creation myths, and the accounts of wanderings and adventures of heroes of the past, are referred to movements among the planets and stars as well as to occurrences or supposed occurrences on earth.