Whenever a person strives, by the help of dialectic, to start in pursuit of every reality by a simple process of reason, independent of all sensuous information - never flinching, until by an act of the pure intelligence he has grasped the real nature of good - he arrives at the very end of the intellectual world.
PlatoIt was Plato, according to Sosigenes, who set this as a problem for those concerned with these things, through what suppositions of uniform and ordered movements the appearances concerning the movements of the wandering heavenly bodies could be preserved.
Plato