“Time (14:155d), like motion and place, received its first definition as a natural concept from Aristotle, who identified it as “the number of motion according to before and after.” This definition develops from three inductive determinations that successively establish (1) time as something of motion, (2) time as continuous, and (3) time as number. (1) Time is not the same thing as motion, for many different motions can take place in the same time, and motions can be fast or slow whereas time remains uniform in flow. On the other hand, time inevitably accompanies motion, for where there is no awareness of motion or change there is no passage of time. (2) Time is continuous because it is associated with motion that traverses a continuous magnitude. A continuum is formally one but materially made up of parts: these parts, joined to each other by indivisibles, constitute an order of local before and after. A motion that traverses such a spatial continuum has also an order of before and after, as does time’s passage, e.g., when punctuated by the sun’s rising and setting, the moon’s phases, the ebb and flow of the tides, the position of hands on a dial. (3) Time is numbering of the successive ‘nows’ that serve to mark its passage. To grasp its being one must visualize a before and after under the common aspect of their being a now (10:547d) and count them as two nows, i.e., as a now-before and a now-after. These nows, the correlates of the here-before and there-after in motion, are the numbered terminals of the continuum that itself is time. The numbering referred to here is not that of an absolute or mathematical number [64.1] divorced from passage. Time is rather numbered number, the number of and in motion that is indissociable from its flux.” (PART 1. // CHAPTER 3 NATURAL PHILOSOPHY // [Section] §19. PLACE AND TIME // [paragraph] 4 // [pages] 53 and 54)
Obiter Dicta: Modern physics speaks of space-time. The concept of space-time better describes movements in the universe and, especially, is effective in describing relativistic (i.e. near light speed) effects. Space-time may be an actual thing or a mathematical construct which accomplishes these better descriptions. Space-time, as either an actual thing or a mathematical construct combines the three dimensions of space with a dimension of time.
Key: For an explanation of the reference and cross reference forms used in this book (e.g. [§19.6] and (11:292c), see previous posts in this blog entitled “The Elements of Philosophy: Preface (7)” and “The Elements of Philosophy: Preface (8)”.