The history of astrology can now be traced back to ancient Babylonia, and indeed to the earliest phases of Babylonian history, in the third millennium B.C. In Babylonia as well as in Assyria as a direct offshoot of Sumerian culture (or in general the Mesopotamian culture), astrology takes its place in the official cult as one of the two chief means at the disposal of the priests (who were called bare or “inspectors”) for ascertaining the will and intention of the gods, the other being through the inspection of the liver of the sacrificial animal.
The earliest extant Babylonian astrology text is the Enuma Anu Enlil (literally meaning “When the gods Anu and Enlil…”), dating back to 1600 B.C. This text describes various astronomical omens and their application to national and political affairs. For example, a segment of the text says: “If in Nisannu the sunrise appears sprinkled with blood, battles. Nisannu is the Babylonian month corresponding to March/April in the Western calendar.
The Babylonian priests accordingly applied themselves to the task of perfecting a system of interpretation of the phenomena to be observed in the heavens, and it was natural that the system was extended from the moon, sun and five planets to the more prominent and recognizable fixed stars.
The interpretations themselves were based (as in the case of divination through the liver) chiefly on two factors:
1) On the recollection or on written records of what in the past had taken place when the phenomenon or phenomena in question had been observed.
2) Association of ideas – involving sometimes merely a play upon words – in connection with the phenomenon or phenomena observed.
Thus, if on a certain occasion, the rise of the new moon in a cloudy sky was followed by victory over an enemy or by abundant rain, the sign in question was thus proved to be a favourable one and its recurrence would thenceforth be regarded as a omen for good fortune of some kind to follow. On the other hand, the appearance of the new moon earlier than was expected was regarded as unfavourable, as it was believed that anything appearing prematurely suggested an unfavourable occurrence.