Special relations were believed to exist between particular celestial bodies

Special relations were believed to exist between particular celestial bodies 

and their varied motions, configurations with each other, and the processes of generation and decay apparent in the world of fire, air, water, and earth. These relations were sometimes regarded as so complex that no human mind could completely grasp them; thus, the astrologer might be readily excused for any errors. A similar set of special relations was also assumed by those whose physics was more akin to that of the Greek philosopher Plato. For the Platonic astrologers, 

the element of fire was believed to extend throughout the celestial spheres, and they were more likely than the Aristotelians to believe in the possibility of divine intervention in the natural processes through celestial influences upon the Earth, since they believed in the deity’s creation of the celestial bodies themselves. The role of the divine in astrological theory varies considerably. In its most rigorous aspect, astrology postulates a totally mechanistic universe, denying to the deity the possibility of intervention and to man that of free will; as such, it was vigorously attacked by orthodox Christianity and Islam. 

For some, however, astrology is not an exact science like astronomy but merely indicates trends and directions that can be altered either by divine or by human will. In the interpretation of Bardesanes, a Syrian Christian scholar (154–c. 222)—who has often been identified as a Gnostic (a believer in esoteric salvatory knowledge and the view that matter is evil and spirit good)—the motions of the stars govern only the elemental world, leaving the soul free to choose between the good and the evil. Man’s ultimate goal is to attain emancipation from an astrologically dominated material world. Some astrologers, such as the Harranians (from the ancient Mesopotamian city of Harran) and the Hindus, 

regard the planets themselves as potent deities whose decrees can be changed through supplication and liturgy or through theurgy, the science of persuading the gods or other supernatural powers. In still other interpretations—e.g., that of the Christian Priscillianists (followers of Priscillian, a Spanish ascetic of the 4th century who apparently held dualistic views)—the stars merely make manifest the will of God to those trained in astrological symbolism. Significance of astral omens The view that the stars make manifest the divine will is closest to the concept that lies behind the ancient Mesopotamian collections of celestial omens. Their primary purpose was to inform the royal court of impending disaster or success. 

These might take the forms of meteorological or epidemic phenomena affecting entire human, animal, or plant populations. Frequently, however, they involved the military affairs of the state or the personal lives of the ruler and his family. Since the celestial omina were regarded not as deterministic but rather as indicative—as a kind of symbolic language in which the gods communicated with men about the future and as only a part of a vast array of ominous events—it was believed that their unpleasant forebodings might be mitigated or nullified by ritual means or by contrary omens.

 The bāru (the official prognosticator), who observed and interpreted the celestial omina, was thus in a position to advise his royal employer on the means of avoiding misfortunes; the omens provided a basis for intelligent action rather than an indication of an inexorable fate.