The unmove mover is a philosophical concept described by Aristotle as the first cause that set the universe into motion. As is implicit in the name, the "unmoved mover" is not moved by any prior action. In his book Metaphysics, Aristotle describes the unmoved mover as being perfectly beautiful, indivisible, and contemplating only the perfect contemplation: itself contemplating. The Unmoved Mover is also referred to as the Prime Mover.