Once upon a time, Astrology was a big thing. Astrologers ruled the world. Now they clatter in the back pages of second-rate magazines. Why were they so big and what’s happened to them?
We shall begin by following a line of thought that was very strong in many parts of the classical world. So strong, it was reason enough to deport Anaxagoras from Athens (he was advocating the stars were nothing but “hot stones in the sky”). The Epicureans made the fight against this view a focal point of their moral philosophy.
So, imagine you live in a society with a technology which is less than modern – there are no cars, no planes, etc. Now, observe: what things have “innate movement” (to borrow the Aristotelian term)? Living things, of course. Only living things can move without being moved by an external force.
Our second observation is this: all living things decease (given enough time).
All? Well, look at the sky – there you will find heavenly bodies moving perpetually in well-ordered paths. If living things are the only candidates for self-induced movement, then the heavenly bodies must be alive. They are also perpetual, hence immortal. They also seem to be moving in a nice circular fashion; hence they must be highly intelligent sentient beings (they know geometry! And circles are the most perfect of geometric forms).