Astronomical Images : Continuous time: proof that there is no first period during which a thing comes to rest

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. Aristotle's position is that spatial magnitude is continuous; movement is continuous because it moves through continuous space; and time is continuous because it is occupied by continuous movement. In <i>Physics</i>, book 6, chapter 8, Aristotle argues that there is no irreducible earliest stage of a thing coming to rest. In this figure, time is represented as a bar with serrated edges, presumably indicating divisibility. The two points with round markers represent a part of time, AB. The circle is defined as the moving thing being brought to rest. Suppose AB were an irreducible earliest stage of motion coming to rest. Then AB cannot be an indivisible moment because (it has already been established) that no motion can occur in an indivisible instant since it is possible for a part of the motion to take place in a part of the time. If AB is divisible, the process of coming to rest must be going on in every part of the proper time of that process. The proper time occupied by a process of coming to rest is a stretch of time, not an indivisible instant, and any stretch of time is divisible without limit. Therefore, there will be no assignable period of time such as AB that can mark an irreducible earliest stage of the process. (Aristotle, <i>Physics</i> VI.8.239a1-10, trans. Wicksteed and Cornford.)</p>