Astronomical Images : Aristotelian principles of motion

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 5, Aristotle shows that a force which can move a given load a certain distance in a certain time can move half the load either twice as far in the same time or the same distance in half the time. The first image demonstrating this argument (on the previous page of this edition, fol. 92r) established two hands labelled A as the moving agent, circle B as the mobile, C as the distance traversed and D, the bar below, as the time taken. The woodcuts on this following page serve to establish the effect of halving the load; in the woodcut at the top, the mobile is halved and C the distance traversed has been doubled. The bar below is intended to indicate a halfway point of the original time but the respective mark is missing. This woodcut illustrates the principle that A will move ½ B over distance 2 C in time D, and A will move ½ B over distance C in time ½ D. In the woodcut at the bottom, the bar shows time D, the single hand E is defined as half of the power A, a half circle B is half the mobile, and C is the distance traversed. It shows that ½ A will move ½ B over distance C in time D. (Aristotle, <i>Physics</i> VII.5.249b27-250a9, trans. Wicksteed and Cornford.)</p>