Astronomical Images : Proof that there cannot be an infinite chain of movers and the moved

Aristotle

Astronomical Images

<p style='text-align: justify;'>This work comprises Aristotle's <i>Physics</i> and Thomas Aquinas's commentary edited by the Augustinian, Timoteo Maffei of Verona (d. 1470). Aristotle discussed the nature of motion in the latter books of <i>Physics</i>, often referring to figures to elucidate his points. These figures were not always illustrated, and there was no traditional stock of figures like the wind diagrams or concentric circles associated with the Aristotelian analysis of motion. This edition makes an effort to supply such figures. In <i>Physics</i>, book 7, chapter 1, Aristotle shows that if there is a series of a moving thing and its mover, the series cannot be unlimited. One proof is as follows: the members of the series will all have distinct motions which occur simultaneously in the finite time occupied by one of them. Supposing the motions to be all equal or to increase as we advance along the series, their sum would be infinite ' an infinite in a finite time, which is impossible. (Aristotle, <i>Physics</i> VII.1.242a17-243a3, trans. Wicksteed and Cornford.) In this woodcut, the circles in the top row indicate the moving thing, the smaller circles below it the motion for each, and a period of time is indicated by a bar.</p>