The
unmoved mover (,
ho ou kinoúmenos kineî, "that which moves without being moved") or
prime mover is a
monotheistic concept advanced by
Aristotle, a polytheist, as a primary cause or "mover" of all the motion in the
universe. As is implicit in the name, the "unmoved mover" moves other things, but is not itself moved by any prior action. In Book 12 (Greek "Λ") of his
Metaphysics, Aristotle describes the unmoved mover as being perfectly beautiful, indivisible, and contemplating only the perfect contemplation: itself contemplating. He equates this concept also with the
Active Intellect. This Aristotelian concept had its roots in
cosmological speculations of the earliest Greek "
Pre-Socratic" philosophers and became highly influential and widely drawn upon in
medieval philosophy and
theology.
St. Thomas Aquinas, for example, elaborated on the Unmoved Mover in the
Quinque viae.