Avempace was a critic of Ptolemy and he worked on creating a new theory of velocity to replace the one theorized by Aristotle. Two future philosophers supported the theories Avempace created, known as the Avempacean dynamics. These philosophers were Thomas Aquinas, a Catholic priest, and John Duns Scotus. Galileo Gallilei went on and adopted Avempace's formula and said "that the velocity of a given object is the difference of the motive power of that object and the resistance of the medium of motion" in the Pisan dialogue.