Aristotle believed that all movement depends on there being a mover. For Aristotle, movement meant more than something travelling from A to B. Movement also included change, growth, melting, cooling, etc. He argued that behind every movement there must be a chain of events that brought about the movement that we observe taking place. He argued that this chain of events must lead back to something which moves but is itself unmoved. Also,in Aristotle’s view, change is eternal.
There cannot have been a first change, because something would have to have happened just before that change which set it off, and this itself would have been a change, and so on. Aristotle calls this source of all movement the Prime Mover. The Prime Mover to Aristotle is the first of all substances, the necessary first sources of movement which is itself unmoved. It is a being with everlasting life, and in metaphysics Aristotle also refers to this as ‘God’. The Prime Mover causes the movement of other things, not as an efficient cause, but as a final cause.
In other words, it does not start off the movement by giving it some kind of push, but it is the purpose, or end of the movement. This is important for Aristotle, because he thought that an effective cause(giving a push), would be affected itself by the act of pushing. Aristotle believed the prime mover causes things to move by attraction in much the same way that a pretty flower attracts a bee. The flower attracts the bee but cannot be said to be changed in the process. Aristotle said that the Prime Mover had to be immaterial.
It could not be made of any kind of stuff, because matter is capable of being acted upon, it has the potential to change. Since it is immaterial, it cannot perform any kind of physical action. Therefore, Aristotle thought, the activity of the Prime Mover, God, must be purely spiritual and intellectual and the activity of God is thought. He continues, ‘God is a thought of a thought’ . At the end of this line of argument, Aristotle comes to the conclusion that God knows only himself; so he does not know this physical world where we live and act. He does not have a plan for we inhabitants, neither is he affected by our actions.