BOOK VIII.'

1. How metaphysics, which is a science of the "ens," is concerned with capacity, dú

ναμις.

CHAPTER I.

CONCERNING Substance, then-I mean, concerning that which is primarily entity, and to which all the rest of the categories of entity are referred-we have declared our sentiments. For according to the definition of substance are denominated the other entities, viz. both quantity, and quality, and the rest of the things that are predicated in this way; for all such will involve the definition of substance, as we have asserted in our earliest dissertations.2 But since entity is denominated partly as quiddity, or quality, or quantity, but partly according to capacity and actuality, and according to work, let us frame certain distinctions and definitions as regards both capacity and actuality; and, in the first instance, as regards that capacity, or potentiality, which is spoken of as such with especial precision: not, to be sure, that this is of service towards the advancement of our present design, for potentiality and actuality extend further than things merely predicated according to motion. But when we have spoken our opinions concerning this in our definitions, as regards energy, we shall make matters plain concerning the other points likewise.

2. Several

tiality, or capa

That, indeed, therefore, potentiality is predimodes of poten-cated in many ways, and that the possession of city, enume- potentiality is expressed in many ways, has been settled by us elsewhere.3 But as many of these as are styled potentialities equivocally may be omitted; for

rated.

1 In the eighth book-ninth according to some-Aristotle considers the subject of capacity and energy with more minuteness. It is well worthy of study, not merely for the distinctions which are found drawn in it, but also for the admirable classification of capacities, or potentialities, which it contains.

2 Vide book VI. chap. i.

3 In the fourth book,-his book of metaphysical definitions,-where the term dúvaus, in its various significations, is fully explained. Vide chap. xii. of that book.

some capacities, or potentialities, are denominated capacities by reason of a certain similarity (as in geometry we speak of potentiality in this way), and things that are potential and impotential we call such in regard of their being, in a certain respect, endued with such a capacity, or not being so. As many potentialities, however, as are referred to the same form or species are all certain first principles, and are predicated in reference to one primary potentiality,' which is a first principle of change in another body, so far forth as it is another. For there is a capacity, on the one hand, of being passive, which, in the actual subject of passion, constitutes a first principle of a passive state through the intervention of another body, so far forth as it is another. There is, on the other hand, the habit of impassivity, such as tends towards a condition which is worse, and the habit of corruption, which arises from the instrumentality of another body, so far forth as it is another-I mean, a first principle capable of bringing about a change. For in all these definitions is inherent the definition of the primary potentiality just mentioned. And again, these potentialities are styled either those of action. merely, or passion, or subsistence in an excellent manner. Wherefore, also, in the definitions of these are inherent, in a manner, the definitions of the former potentialities.

this enumera

tialities.

It is, therefore, evident that there is, in a 3. Inferences certain respect, one potentiality of action and drawn from passion,-for a thing that is potential is such in tion of potenregard of itself having the potentiality of passiveness, and in regard of another thing having it by reason of this,—and, in another respect, there is a different potentiality. For one kind of potentiality resides in the patient; for, on account of its having a certain first principle, and on account of matter,2 also, being a certain first principle, the subject of the passion is passive, and one thing undergces a change by reason of another; for that which is fat is combustible also: but that which yields in this manner

1 These words are worthy of attention; for by thus making every capacity in its action relative to the operation of a certain other capa city, we ultimately arrive at the primary capacity; and this, according to principles already established, presupposes a something beyond capacity, an activity, the absolute évépyeia, the first cause.

2 ὕλην : somne copies read, ὅλην.

is a thing that is bruised; and in like manner, also, is it with other things. But another kind of potentiality resides in the agent, as the hot, and the capacity of house-building, are involved severally, the former in that which is capable of making a thing warm, and the latter in a person who is qualified to build a house. Wherefore, as far forth as a thing is naturally connected with itself it in no wise undergoes a passive state itself, by reason of its own agency, for it is one thing, and not anything else.

4. What impotentiality is, ἀδυναμία.

And impotentiality, and that which is impotential (now, such is contrary to potentiality), is privation. Wherefore, every potentiality belongs to the same, and subsists according to the same subject with impotentiality. Privation,1 however, is predicated in many ways; for privation is to be found where a thing does not possess something else, and, though fitted by nature for the possession of such, may yet not have it either entirely or when it is fitted by nature and we say either, after this manner, that it is privation, for instance, altogether so, or yet even in some certain respect or other. And, in the case of some things, if being by nature adapted to possess a thing, they may not yet have such by reason of violence, we say that these are subjects of privation in this respect.

1. As to potentialities, some

are not, con

nected with

reason.

CHAPTER II.

SINCE, however, such first principles of potentiality are inherent partly in things that are are, and others inanimate, and partly in things that are animate and contained in soul, and in that portion of the soul which possesses reason, it is evident that also of potentialities some will be devoid of reason, whereas others will be accompanied with reason. Wherefore, all the arts, even such as are constructive, as well as the sciences, are potentialities; for they constitute first principles which are causes of change in another subject, so far forth as it is another. And all those potentialities, indeed, that are The term privation, σrépnois, has been already defined in book IV shap. xxii. 2 Some copies read, καὶ ποιητικα, ἐπίστημαι.

accompanied, or involve any connexion with reason, are productive of contraries; each of those, however, that is devoid of reason is alone productive of one result: as, for instance, that which is hot is productive of the promotion of heat merely, and the medicinal art of disease and health.

tive powers of

classes of po

And a cause of this is the following, that 2. Difference scientific knowledge is reason, and the same in the producreason makes manifest the result produced and these two its privation, though not after the same manner; tentiality acand in one way is this reason that which creates counted for. this knowledge for both, yet in another it affords greater knowledge of the thing in existence than of its privation. Wherefore, it is requisite that such sciences as these should involve a knowledge of contraries; but that of the one it should be thus essentially, and of the other not essentially. for also reason is a knowledge of the one essentially, but of the other, after a certain manner, according to accident, for by negation and ablation it makes manifest the contrary; for primary privation is that which is contrary, and this is an ablation of the other. Since, however, contraries are not inherent in the same thing-now, science is a capacity in respect of the possession of reason, and the soul also possesses a first principle of motion-hence the healthy or salubrious produces health only, and that which is capable of promoting heat-warmth, and of promoting cold-chilliness; but the scientific person produces both. For of both, no doubt, has reason a knowledge, but not in the same manner; and this reason subsists in a soul which possesses a first principle of motion. Wherefore, soul will move both from the same first principle, having effected coherence towards the same thing; wherefore, the things which are potential, or endowed with capacity according to reason, produce contraries to the productions of that which is potential without reason, for one first principle is comprised in reason. But it is evident that also upon the 3. The Tò ev power of action and, passion in an excellent not necessarily

2

! I have followed Taylor's paraphrastic rendering of this passage. 2 What Aristotle means is this, that science presupposes in man a scientific capacity, and that this is to be found in the rational soul, which contains within itself the efficient cause of man's pursuit afte knowledge.

notion of

δύναμις.

involved in the manner there follows the power merely of action or of passion: but in this latter the former is not invariably to be found; for he that acts well must needs also be an agent, but where a person only is an agent it is not necessary, also, that he should act well.

1. False notions

of the Megaric energy being a

school as to

necessary condition for potentiality.

CHAPTER III.1

BUT there are some who say-for instance, those of the Megaric school-that where there is energy, there only is there potentiality, or capacity, but that where there is no energy, there is no potentiality; for example, that the person who does not actually build has not the capacity of building, but that he has the capacity of building when he actually builds, and that it is in like manner, also, with other things. Now, the absurdities which ensue with these speculators it is not difficult to discover. For it is evident that neither will he be a builder if he does not actually build; for the being of a builder consists in the possession of the capacity of building; and in like manner, also, it is the case with the rest of the arts. If, therefore, it is impossible for one to possess arts of this kind, if he has not at any time received instruction in them, and acquired them, and not to be in the possession of them, unless at some time or other he lose them, (for one may do so either through forgetfulness, or a certain affection, or time; for as to the thing itself, that, at any rate, has not fallen into decay, for it is in existence always;) this being the case when there may be a cessation of operation on the part of such a one, he will not have in possession the art, and how will he again forthwith proceed to build in resuming the art which he had lost?

1 Aristotle, by what goes before, is led to attack the Megarian philosophers, who confounded everything with "being," and, therefore, potentiality with energy. The rallying point of the Megarics was the school established at Megara by Euclid, a native of the place; and Aristotle, no doubt, has his eye fixed principally on Euclid, for the latter was a most vehement opponent of the dogmatism of the Peripatetics. Vide Tenneman, p. 98, translated in "Bohn's Philological Library."