Aquinas' first proof is based on his knowledge of Aristotle's prime movers theory. Everything in the world is in state of flux (change) and behind every movement there must be a chain of events that brought about the movement that we see taking place.
What is the idea of Aristotle's prime mover? Did he believe in more than one prime mover? Can we say he called the prime mover 'God'? How can the concepts of efficient cause and final cause be explained? What is different Aristotle's prime mover and Aquinas' first proof?