How did astrology develop from its beginnings?
Astrology was based on two Bayblonian ideas: the zodiac, and the divinity of the heavenly bodies. The Babylonians credited the planets with the influences that one would expect of their respectrive deities. (Great Cites of the Ancient World)
In the religion of ancient Babylon every object and force of nature was supposed to have its own spirit, who could be controlled by magical exorcisims of the shaman or sorcerer priest. (The History of the Nations)