Metaphysics is one of the principal works of Aristotle and the first major work of the branch of philosophy with the same name. The principal subject is "being qua being", or being understood as being. It examines what can be asserted about anything that exists just because of its existence and not because of any special qualities it has. Also covered are different kinds of causation, form and matter, the existence of mathematical objects, and a prime-mover God.

Book VII Chapter 152015-05-12
Since substance is of two kinds, the concrete thing and the formula (I mean that one kind of substance is the formula taken with the matter, while another kind is the formula in its generality), substances in the former sense are capable of destruction (for they are capable also of generation), but
Book VII Chapter 162015-05-11
Evidently even of the things that are thought to be substances, most are only potencies,-both the parts of animals (for none of them exists separately; and when they are separated, then too they exist, all of them, merely as matter) and earth and fire and air; for none of them is a unity, but as it
Book VII Chapter 172015-05-11
Let us state what, i. e. what kind of thing, substance should be said to be, taking once more another starting-point; for perhaps from this we shall get a clear view also of that substance which exists apart from sensible substances. Since, then, substance is a principle and a cause, let us pursue it
Book VIII Chapter 12015-05-10
WE must reckon up the results arising from what has been said, and compute the sum of them, and put the finishing touch to our inquiry. We have said that the causes, principles, and elements of substances are the object of our search. And some substances are recognized by every one, but some have be
Book VIII Chapter 22015-05-10
Since the substance which exists as underlying and as matter is generally recognized, and this that which exists potentially, it remains for us to say what is the substance, in the sense of actuality, of sensible things. Democritus seems to think there are three kinds of difference between things; t
Book VIII Chapter 32015-05-09
We must not fail to notice that sometimes it is not clear whether a name means the composite substance, or the actuality or form, e. g. whether house is a sign for the composite thing, a covering consisting of bricks and stones laid thus and thus, or for the actuality or f
Book VIII Chapter 42015-05-09
Regarding material substance we must not forget that even if all things come from the same first cause or have the same things for their first causes, and if the same matter serves as starting-point for their generation, yet there is a matter proper to each, e. g. for phlegm the sweet or the fat, and
Book VIII Chapter 52015-05-08
Since some things are and are not, without coming to be and ceasing to be, e. g. points, if they can be said to be, and in general forms (for it is not white comes to be, but the wood comes to be white, if everything that comes to be comes from something and comes to be something), not
Book VIII Chapter 62015-05-08
To return to the difficulty which has been stated with respect both to definitions and to numbers, what is the cause of their unity? In the case of all things which have several parts and in which the totality is not, as it were, a mere heap, but the whole is something beside the parts, there is a c
Book IX Chapter 12015-05-07
WE have treated of that which is primarily and to which all the other categories of being are referred-i. e. of substance. For it is in virtue of the concept of substance that the others also are said to be-quantity and quality and the like; for all will be found to involve the concept of substance,
Book IX Chapter 22015-05-07
Since some such originative sources are present in soulless things, and others in things possessed of soul, and in soul, and in the rational part of the soul, clearly some potencies will, be non-rational and some will be non-rational and some will be accompanied by a rational formula. This is why al
Book IX Chapter 32015-05-06
There are some who say, as the Megaric school does, that a thing can act only when it is acting, and when it is not acting it cannot act, e. g. that he who is not building cannot build, but only he who is building, when he is building; and so in all other cases. It is not
Book IX Chapter 42015-05-06
If what we have described is identical with the capable or convertible with it, evidently it cannot be true to say this is capable of being but will not be, which would imply that the things incapable of being would on this showing vanish. Suppose, for instance, that a man-one who did
Book IX Chapter 52015-05-05
As all potencies are either innate, like the senses, or come by practice, like the power of playing the flute, or by learning, like artistic power, those which come by practice or by rational formula we must acquire by previous exercise but this is not necessary with those which are not of this natu
Book IX Chapter 62015-05-05
Since we have treated of the kind of potency which is related to movement, let us discuss actuality-what, and what kind of thing, actuality is. For in the course of our analysis it will also become clear, with regard to the potential, that we not only ascribe potency to that whose nature it is to mo
Book IX Chapter 72015-05-04
What, and what kind of thing, the actual is, may be taken as explained by these and similar considerations. But we must distinguish when a thing exists potentially and when it does not; for it is not at any and every time. E. g. Is earth potentially a man? No-but rather when it has already become see
Book IX Chapter 82015-05-04
From our discussion of the various senses of prior, it is clear that actuality is prior to potency. And I mean by potency not only that definite kind which is said to be a principle of change in another thing or in the thing itself regarded as other, but in general every principle of m
Book IX Chapter 92015-05-03
That the actuality is also better and more valuable than the good potency is evident from the following argument. Everything of which we say that it can do something, is alike capable of contraries, e. g. that of which we say that it can be well is the same as that which can be ill, and has both pote
Book IX Chapter 102015-05-03
The terms being and non-being are employed firstly with reference to the categories, and secondly with reference to the potency or actuality of these or their non-potency or nonactuality, and thirdly in the sense of true and false. This depends, on the side of the objects
Book X Chapter 12015-05-02
WE have said previously, in our distinction of the various meanings of words, that one has several meanings; the things that are directly and of their own nature and not accidentally called one may be summarized under four heads, though the word is used in more senses. (1) There is the
Book X Chapter 22015-05-02
With regard to the substance and nature of the one we must ask in which of two ways it exists. This is the very question that we reviewed in our discussion of problems, viz. what the one is and how we must conceive of it, whether we must take the one itself as being a substance (as both the Pythagor
Book X Chapter 32015-05-01
The one and the many are opposed in several ways, of which one is the opposition of the one and plurality as indivisible and divisible; for that which is either divided or divisible is called a plurality, and that which is indivisible or not divided is called one. Now since opposition is of four kin
Book X Chapter 42015-05-01
Since things which differ may differ from one another more or less, there is also a greatest difference, and this I call contrariety. That contrariety is the greatest difference is made clear by induction. For things which differ in genus have no way to one another, but are too far distant and are n
Book X Chapter 52015-04-30
Since one thing has one contrary, we might raise the question how the one is opposed to the many, and the equal to the great and the small. For if we used the word whether only in an antithesis such as whether it is white or black, or whether it is white or not whi
Book X Chapter 62015-04-30
We might raise similar questions about the one and the many. For if the many are absolutely opposed to the one, certain impossible results follow. One will then be few, whether few be treated here as singular or plural; for the many are opposed also to the few. Further, two will be many, since the d