When a man asks us, What is the Cause? we ought to reply, since the word has many senses, by specifying all the causes which can have a bearing on the case (p. 1044, a. 34). Thus, What is the Cause of man, as Matter? Perhaps the katamenia. What, as Movent? Perhaps the seed. What, as Form? The τ.η.ε. What, as οὗ ἕνεκα? The End. These two last are perhaps both the same (a. 36). Moreover we ought to make answer by specifying the proximate causes (not the remote and ultimate). Thus, What is the Matter of man? We must answer by specifying the proximate matter; not fire and earth, the ultimate and elemental (b. 2).
This is the only right way of proceeding in regard to Essences natural and generable; since the Causes are many, and are what we seek to know. But the case is different in regard to Essences natural, yet eternal. Some of these last perhaps have no Matter at all; or at least a different Matter, having no attribute except local movability (b. 8. Alexander says in explanation: λέγει δὲ τὴν ξύμπασαν τῶν ὀκτὼ σφαιρῶν ἑνάδα — ὕλην οὐ γεννητὴν καὶ φθαρτὴν ἀλλὰ μόνον κατὰ τόπον κινητήν — p. 527, 20-25, Bon.).
Again, in regard to circumstances which occur by Nature, but not in the way of Essence, there is no Matter at all: the subject itself is the Essence. Thus in regard to an eclipse: What is its Cause? What is its Matter? There is no Matter, except the moon which is affected in a certain way. What is the Cause, as Movent — here light-destroying? The earth. Perhaps there is no οὗ ἕνεκα in the case. But the Cause in the way of Form is the rational explanation or definition; and this must include a specification of the Movent Cause, otherwise it will be obscure. Thus, the eclipse is, privation of light; and, when you add — by the earth intervening, you then specify the Movent, and make your definition satisfactory (b. 15).
In defining sleep we ought to say what part of the system is first affected thereby; but this is not clear. Shall we indicate only the animal (as substratum)? But this is not enough. We shall be asked, What part of the animal? Which part first? The heart, or what other part? Next, by what Cause? Lastly, how is the heart affected, apart from the rest of the system? To say — Sleep is a certain sort of immobility, will not be a sufficient definition. We must specify from what primary affection such immobility arises (p. 1044, b. 20).
Since some things exist, and do not exist, without generation or destruction (as Forms, and Points, if there be such things as Points), it is impossible that all Contraries can be generated out of each other, if every generation be both aliquid and ex aliquo. Albus homo ex nigro homine must be generated in a different way from album ex nigro. Now Matter is only to be found in those cases where there is generation and change into each other; in other cases, where no change takes place, there is no Matter. There is a difficulty in understanding how the Matter of each substance stands in regard to the contrary modifications of that substance (p. 1044, b. 29). If the body is potentially healthy, and if disease is the contrary of health, are we to say that both these states are potential? Is water potentially both wine and vinegar? Or are we to say rather that the body is the Matter of health, and that water is the Matter of wine, in the way of acquisition by nature and by taking on the Form to which it tends; and that the body is the Matter of sickness, and wine the Matter of vinegar in the way of privation and of destruction contrary to nature (b. 34)? However, there is here some difficulty: Since vinegar is generated out of wine, why is not wine the Matter of vinegar, and potentially vinegar? Why is not the living man potentially a corpse? Is it not rather the truth, however, that these are accidental or contra-natural destructions (κατὰ συμβεβηκὸς αἱ φθοραί â€” b. 36, i.e., not in the regular appetency and aspirations, according to which the destruction of one Form gives place to a better); and that through such destruction the same Matter which belonged to the living man becomes afterwards the Matter of the corpse; likewise the Matter of wine becomes, through the like destruction, Matter of vinegar — by a generation like that of night out of day? Changes of this sort must take place by complete resolution into the original Materia Prima (εἰς τὴν ὕλην δεῖ ἐπανελθεῖν — a. 3); thus, if a living animal comes out of a dead one, the latter is first resolved into its elements, and then out of them comes the living animal. So vinegar is first resolved into water, then out of the water comes wine (a. 5).
We shall now revert to the difficulty recently noticed, about Definitions and Numbers. What is the cause that each number and each definition is One? In all cases where there are several parts not put together as a mere heap, but where there is a Whole besides the parts, there must be some cause of this kind. With some bodies, contact is such cause; with others, viscosity (γλισχρότης — p. 1045, a. 12), or some other affection. But the definition is one complex phrase, not by conjunction like the Iliad, but One by being the definition of one subject (a. 14). Now what is it which makes the subject man, One? Why is he One and not Many, say animal and a biped — more especially if there exist, as the Platonists say, a Self-animal and a Self-biped? Why are not these two αὐτά the man (διὰ τί γὰρ οὐκ ἐκεῖνα αὐτὰ ὁ ἄνθρωπός ἐστι; — a. 17), so that individuals are men by participation not of one Self-man, but of the two — Self-animal, Self-biped? On this theory altogether, it would seem that a man cannot be One, but must be Many — animal and biped. It is plain that in this way of investigation the problem is insoluble.
But if, as we say (p. 1045, a. 23), there be on one side Matter, on the other side Form — on one side that which is in Potency, on the other side that which is in Act (a. 24) — the problem ceases to be difficult. The difficulty is the same as it would be if the definition of himation were, round brass: the word himation would be the sign of that definition, and the problem would be, What is the Cause why round and brass are One? But the difficulty vanishes, when we reply that one is Matter, the other Form. And, in cases where generation intervenes, what is the Cause why the potential Ens is actual Ens, except the Efficient (παρὰ τὸ ποιῆσαν — a. 31)? There is no other Cause why the sphere in potency is a sphere in actuality: such was the τ.η.ε. of each (τοῦτ’ ἦν τὸ τ.η.ε. ἑκατέρῳ — a. 33). Of Matter there are two varieties, the Cogitable and the Perceivable; and, in the Definition, a part is always Matter, a part is Form or Energy; as when we define the circle — a plane figure. (Aristotle argues:— On the Platonic theory that Ideas or Forms are Entia, separate from particulars, self-existent, and independent of each other, no cause can be assigned for the coalescence of any two or more of them into one; e.g. animal and biped, into man. But upon my theory, Form and Matter, Power and Act, are in their own nature relative to each other. It is their own inherent nature to coalesce into one, or for Power to pass into Act. This is the cause of their unity: no other cause can be found or is necessary. See Alexander, p. 531.)
In those cases where there is no Matter, either cogitable or perceivable, as in the Categories, Hoc Aliquid, Quale, Quantum, &c., each of them is, in itself and at once, both Ens and Unum (p. 1045, b. 2). Hence neither Ens nor Unum is included in the Definitions, and the τ.η.ε. is, in itself and at once, both Ens and Unum. No other cause can be assigned why each of these is Ens and Unum; each of them is so, at once and immediately; yet not as if they were all included in Ens or Unum as common genera; nor as if they were apart and separable from particulars (b. 7).
Philosophers, who do not adopt this opinion, resort to various phrases, all unsatisfactory, to explain the coalescence or unity of the elements included in the Definition. Some call it μέθεξις, but they give no cause of the μέθεξις; others συνουσία, or σύνδεσμος, or σύνθεσις — of soul with body, as definition of life. But we might just as well use these phrases on other occasions, and say that to be well was a synthesis of the soul with health; that the brazen triangle was a σύνδεσμος of brass with triangle; that white was a synthesis of superficies with whiteness (p. 1045, b. 15). These phrases carry no explanation; and these philosophers get into the difficulty by taking a wrong point of departure. They first lay down Power as different from Entelechy, and then look for an explanation which makes them one (αἴτιον δ’ ὅτι δυνάμεως καὶ ἐντελεχείας ζητοῦσι λόγον ἑνοποιὸν καὶ διαφοράν — p. 1045, b. 16, Schwegler observes that the two last words are loosely put, and that the clear words to express what Aristotle means would be: ζητοῦσι λόγον ἑνοποιὸν ὑποτιθέντες διαφοράν — Comm. II. p. 154.). But the truth is that Power and Entelechy are not essentially two, but only different aspects of one and the same. The Last Matter and the Form are the same; but the first is in potency, the second in perfect actuality (“Stoff und Form, Potenzielles und Actuelles, sind eins und dasselbe auf verschiedenen Entwicklungsstufenâ€� — Schwegler II. p. 151). To enquire in any particular case what is the cause of this One, is the same as to enquire generally the cause of Unity. Each thing is a certain One; the Potential and the Actual are One, in a certain way (b. 20). So that no other Cause can be found except the Movent or Efficient — that which moved the matter out of Potency into Actuality. As to those things which have no Matter, each of them is One immediately and per se (b. 23).