The First Way: Argument from Motion
- Our senses prove that some things are in motion.
- Things move when potential motion becomes actual motion.
- Only an actual motion can convert a potential motion into an actual motion.
- Nothing can be at once in both actuality and potentiality in the same respect (i.e., if both actual and potential, it is actual in one respect and potential in another).
- Therefore nothing can move itself.
- Therefore each thing in motion is moved by something else.
- The sequence of motion cannot extend ad infinitum.
- Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.