Aristotle argued that certain kinds of things have “a principle of motion and of stationariness,” an “innate impulse to change.” Artificial things do not have such an impulse or principle, insofar as they are products of art, though “in so far as they happen to be composed of stone or of earth or of a mixture of the two, they do have such an impulse.” Such things that have such a principle or impulse toward motion are things that “have a... Read more