“At this point in Theta 8, we have completed, by the mediation of the terms telos [end] and ergon [completed work], the justification of the equivalence between the superior terms of the analogy, energeia [act], kinesis [motion], and ousia [“substance”], just as we have justified that between the inferior terms, dunamis [power] and hyle [matter]. But in so doing, we have also subsumed one analogical relation under the other, by showing in the correlation dunamis–kinesis a particular case of the correlation hyle–ousia: power serves as a means for matter to attain the form posed as end, and indeed as a means for the coming to be of substance as unity of matter and form, movement itself being able to serve, in the case of transitive activities, as end and as realization of essence. We have thus completed the transition from the kinetic sense to the ontological sense of dunamis and energeia, and at the same time established the priority of the ontological sense over the kinetic sense.”

“The end of Theta 8 nonetheless begins another process: this no longer aims at showing the ontological sense of dunamis and energeia, but at extending their field of application beyond the corruptible sensible substances” (Aubry, Dieu san la puissance, 2nd ed., ch. 4, p. 141, my translation throughout, Becker number citations to the Greek text omitted). 

Aristotle regards the stars as eternal (or more precisely, sempiternal) sensible beings, because on a human time scale their motions and other characteristics appear to be unchanging. From this perspective, he understands not only the first cause but all astronomical entities in terms of pure act (energeia), without any admixture of power (dynamis), or of being that is only in-potentiality (dynamei). But these are still sensible beings subject to motion, so they occupy an intermediate place between terrestrial things and the first cause.

This association with eternity and pure act goes along with his view that unlike terrestrial things, the stars move by necessity. Again, for Aristotle this just means always in the same way. Here he does speak of “what cannot not be”, but I think this is only a consequence of his definition of necessity. It is a reflection of the logical truth that if we say something always occurs in a certain way, then we are committed to saying it cannot not occur in that way, simply because “always” implies “never not” — and not anything stronger than that.

Aristotle’s argument, which ultimately aims to draw conclusions about the first cause from an analysis of things closer to us, is made somewhat easier by the existence of this intermediate case of eternal sensible substances in his conceptual schema. But it does not seem to me that any of his arguments about pure act really depends on this common-sense assumption that the stars are eternal.

Even if we have a different conception of astronomical entities, according to which they just exist on a much longer time scale than terrestrial things, the conceptual distinction of a separable pure act remains available to us. (Hegel, for example, develops a version of it that has no connection to astronomy, and instead appeals only to the lasting ethical and cultural achievements of rational beings.) (See also Grammatical Prejudice?.)

“Act can in effect only be attributed to the eternal sensible substances on the condition of being dissociated from dunamis, redefined as the power of contradiction (in the same way, it will only be able to be extended in book Lambda to the simple substance on the condition of the exclusion of movement). But insofar as Theta 6 introduced it as indissociable from its correlation with in-potentiality, it is the very understanding of the notion of act that seems to be called into question: how do we understand energeia without in-potentiality? What kind of act is it that is no longer the unity of matter and form in the end? Can we under these conditions maintain its identity to ousia?”

“These questions will only find a definitive response in book Lambda. Theta 8 is content to begin the process of the extension of energeia: the notion is in effect applied to the eternal sensible substances. For this application allows us to extract yet another sense, and a more fundamental one, of the anteriority of act according to ousia: if act is anterior to in-potentiality according to ousia, this is also because, contrary to in-potentiality, it characterizes such substances. For these are more so substances than the perishable sensible substances” (ibid).

In the analysis of things around us that are in becoming, we see the underlying modalities of in-potentiality and in-act functioning in an interdependent way. But if we look at in-potentiality and in-act just as modalities, only one depends on the other. That is just what the priority of act is intended to convey.

Aubry sees a new distinction introduced here for the first time. Aristotle first explicitly mentions that dynamis may have effects that are not only contrary but contradictory, and at the same time specifies in-potentiality is a mode of being that can be resolved to act in contradictory alternative ways. But it seems to me that this has been implicit from the moment that talk about potentiality for contraries was introduced. And in the bigger picture, Aristotle’s whole insistence on the priority of act over potentiality and the asymmetry in the relation between them seems to have been designed from the start to support considerations of the independence of act from potentiality.

There could be no potentiality without something being in act. But it is very clear that for Aristotle, the relation of potentiality to act is asymmetrical. By contrast, activity and passivity are completely symmetrical, so it is impossible to have the one without the other. But potentiality depends on act, whereas act seems to be the very thing that makes something an ousia malista, or what is most of all a substance. The criterion for this is precisely “separability” or independence relative to other things. Potentiality seems ubiquitous to us because it is a necessary component of all the terrestrial things we are accustomed to, not because act in principle has any dependency on it. Or such seems to be Aristotle’s argument.

Aubry already emphasized in her reading of book Zeta that for Aristotle, what distinguishes ousia malista is its separability, or ability to have being on its own. But Zeta’s discussion focuses on perishable sensible substances, and therefore on applying this kind of separability to concrete composites of form and the familiar kind of (non-celestial) matter. Here for the first time Aristotle explicitly addresses eternal sensible substances.

“The correlation of in-potentiality and act is here broken: act is no longer presented as the end and the principle of dunamis, but as excluding it. Energeia and dunamis name opposed modes of being, where one is proper to the necessary, as that which cannot not be, the other to the contingent, as that which can be or not be. Dissociated from dunamis, energeia remains on the other hand associated with kinesis [motion]: in effect, the eternal sensible substances are in movement. But movement in their case is not the transition from one state of being to another, or from in-potentiality to act: exclusive of in-potentiality, it is confounded with their very act — by which we indeed verify that for certain beings kinesis can serve as telos [end] and as manifestation of being. Finally, dissociated from in-potentiality, this movement remains no less associated with matter, or at least a certain kind of matter” (pp. 142-143).

“[E]ven though the correlation of in-potentiality to act has been broken among the eternal sensible substances, it operates again between these and the corruptible sensible substances” (pp. 143-144).

“[A]ct can be not only another name for the ousia composed of matter and form (or for matter as realized in a form, the form in a matter), but for ousia as such. Act thus comes to name a superior degree of being, which, insofar as it is exempt from in-potentiality, is characterized by necessity, understood as the impossibility of not being” (p. 144).

“In-potentiality, as being able to be or not be, names an inferior degree of being, which characterizes contingency, but remains no less correlated to act in a relation of dependency that also marks act’s anteriority according to ousia” (ibid).

Aristotle’s text does clearly suggest that astronomical entities are somehow superior to terrestrial things, and it relates this superiority to the notion that they are purely in-act. But a modern understanding of astronomical entities expressed in Aristotelian terms would be that contrary to what Aristotle thought, they are not in fact purely in-act.

There is, however, an alternate basis for vindicating the “superiority” of the celestial over the terrestrial. The cosmos is inconceivably more vast than the earth, and for modern science too causally subsumes and includes it, analogous to the way that Aristotle thought it did.

Since childhood I have felt a fascination for the vastness of space and time, that could include distant galaxies and dinosaurs. Completely unlike Pascal’s famous terror at being so small in this vastness, I experienced this with only the profound wonder that Aristotle identifies as the beginning of philosophy.

Even if we do not regard astronomical entities as eternal sensible substances, I think Aristotle for his part would have no trouble endorsing Kant’s expression of the two great wonders, “the starry heavens above and the moral law within”.

Next in this series: Book Theta: Summing Up