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Although the stated purpose of Physics viii 8 is to prove that only circular locomotion is infinitely continuous, it is generally recognized that a major sub-theme of the chapter has to do with the unity of change and centers on Zeno’s dichotomy paradox. According to one influential account of this sub-theme, Aristotle returns to the dichotomy paradox in Physics viii 8, primarily to engage in a defensive maneuver. In Physics vi, while focused on the infinite divisibility of change instead of its identity conditions, Aristotle left open the possibility that occurrences that are ‘one change’ could have infinitely many parts that are also ‘one change’.1 By Physics viii 8, however, Zeno has brought Aristotle to realize that if this possibility is admitted, then what one chooses to call ‘one change’ is to a large extent arbitrary. But this Aristotle cannot countenance, because his entire theory of change is built upon the concept of a change as a thing uniquely definable as the passage from a particular state to a particular state. In Physics viii 8, then, Aristotle seeks to avoid this result by ‘refining’ the definition of ‘one change’ so that ‘one change’ can no longer have parts that are also ‘one change’ and by invoking the metaphysical machinery of the act-potency distinction to give a positive characterization of the difference between change parts and change wholes.2 According to Michael White, Aristotle ‘refines’ his definition of ‘one change’ in Physics viii 8 by strengthening the criteria of Physics v 4; criteria, which, White is correct to point out, do nothing to prevent this result on their own.3 According to White, this ‘refinement’ consists in adding, to the criteria of Physics v 4 (i.e., the criteria that ‘one change’ must be in a continuous time, have a single subject throughout, and proceed throughout from a terminus of the same species to a contrary terminus of the same species), the additional condition that an occurrence that is ‘one change’ must be bracketed by periods of rest and contain no periods of rest..

Part I: Dimensions of time's enigma -- Is time real? -- Eleaticism, temporality, and time -- The makings of a temporal universe -- Pastness and futurity -- Synchronicity and synchronicity -- Temporal pace and measurement -- Presentness or the present -- Aristotle's real account of time -- Parmenidean time and the impossible now -- Cosmic motion and the speed of time -- Time as the motion of the cosmos -- Time as the cosmos itself -- Time as motion and all change -- Temporal cognition and the return of the now -- Real temporality in an Aristotelian world -- Does Aristotle refute eleaticism? -- Bisection argument I -- Bisection argument II -- Bisection argument III -- Plotinus' vitalistic platonism and the real origins of time -- Temporality, eternality, and Plotinus' new metaphysic -- Plotinus' critique of Aristotelian motion -- Indefinite temporality and the measure of motion -- Plotinus' neoplatonic account of time.

Traditionally, this puzzle has been solved in various ways. Aristotle, for example, distinguished between “accidental” and “essential” changes. Accidental changes are ones that don't result in a change in an objects' identity after the change, such as when a house is painted, or one's hair turns gray, etc. Aristotle thought of these as changes in the accidental properties of a thing. Essential changes, by contrast, are those which don't preserve the identity of the object when it changes, such as when a house burns to the ground and becomes ashes, or when someone dies. Armed with these distinctions, Aristotle would then say that, in the case of accidental changes, (1) and (2) are both false—a changing thing can really change one of its “accidental properties” and yet literally remain one and the same thing before and after the change.

Taking very seriously its anti-Parmenidean character, this essay locates a radically temporalized ontology at the heart of Aristotle’s Physics. We first concentrateon Aristotle’s discussion of kinêsis or ‘change’ as always between opposites, drawing the conclusion that the archai that govern and constitute a change, as opposites, cannot be present in the change itself. Thus, change is what it is by virtue of what is necessarily not present. We then draw the implications of this discussion for chronos or ‘time,’ defined in Book IV of the Physics as “the number of change.” Here, we uncover the ecstatic present moment of natural, changing things, a present constituted by its past and future, which is to say by what is emphatically not present.

In Book IV, Chapter 11 of the Physics, Aristotle claims that ‘the before and after’ exists in time because it also exists in change, and it exists in change because it also exists in magnitude, and, further, that ‘time follows change’ and ‘change follows magnitude’.1 This is usually taken to mean that moments of time correspond to momentary stages of changes, and that momentary stages of changes correspond to points in magnitudes, so that time derives its ‘before and after’ from that of change, and change from that of magnitude.2 But this is widely thought to land Aristotle in the following diffi culty: If Socrates walks between points A and C, for instance, he can either proceed from point A to point..

In Physics IV 14, 223a16-223a29 Aristotle raises two questions: (Q1) How is time related to the soul? (Q2) Why is time thought to be in everything? Aristotle's juxtaposition of these questions indicates some relation between them. I argue that Aristotle is committed to the claim that time only exists where change is countable. Aristotle must answer (Q2) in a way that doesn't conflict with this commitment. Aristotle's answer to (Q1) offers him such a way. Since time is change qua countable, time is dependent on souls capable of counting. But the thing that time is, change, is not so dependent. Likewise, time is not located in everything, but change, the substratum of time, is. This answers (Q2) in a way that's compatible with Aristotle's commitments.

What is the relation between time and change? Does time depend on the mind? Is the present always the same or is it always different? Aristotle tackles these questions in the Physics. In the first book in English exclusively devoted to this discussion, Ursula Coope argues that Aristotle sees time as a universal order within which all changes are related to each other. This interpretation enables her to explain two striking Aristotelian claims: that the now is like a moving thing, and that time depends for its existence on the mind.