Lecture 10 — The difference between generation and alteration.

Next we must state what the difference is between coming-to-be and 'alteration'—for we maintain that these changes are distinct from one another.

Since, then, we must distinguish (a) the substratum, and (b) the property whose nature it is to be predicated of the substratum; and since change of each of these occurs; there is 'alteration' when the substratum is perceptible and persists, but changes in its own properties, the properties in question being opposed to one another either as contraries or as intermediates. The body, e.g. although persisting as the same body, is now healthy and now ill; and the bronze is now spherical and at another time angular, and yet remains the same bronze.

But when nothing perceptible persists in its identity as a substratum, and the thing changes as a whole (when e.g. the seed as a whole is converted into blood, or water into air, or air as a whole into water), such an occurrence is no longer 'alteration'.

It is a coming-to-be of one substance and a passing-away of the other—especially if the change proceeds from an imperceptible something to something perceptible (either to touch or to all the senses), as when water comes-to-be out of, or passes-away into, air: for air is pretty well imperceptible.

If, however, in such cases, any property (being one of a pair of contraries) persists, in the thing that has come-to-be, the same as it was in the thing which has passed-away—if, e.g. when water comes-to-be out of air, both are transparent or cold—the second thing, into which the first changes, must not be a property of this persistent identical something. Otherwise the change will be 'alteration.' Suppose, e.g. that the musical man passed-away and an unmusical man came-to-be, and that the man persists as something identical. Now, if 'musicalness and unmusicalness' had not been a property essentially inhering in man, these changes would have been a coming-to-be of unmusicalness and a passing-away of musicalness: but in fact 'musicalness and unmusicalness' are a property of the persistent identity, viz. man. (Hence, as regards man, these changes are 'modifications'; though, as regards musical man and unmusical man, they are a passing-away and a coming-to-be.) Consequently such changes are 'alteration.'

When the change from contrary to contrary is in quantity, it is 'growth and diminution'; when it is in place, it is 'motion'; when it is in property, i.e. in quality, it is 'alteration': but, when nothing persists, of which the resultant is a property (or an 'accident' in any sense of the term), it is 'coming-to-be', and the converse change is 'passing-away'.

"Matter," in the most proper sense of the term, is to be identified with the substratum which is receptive of coming-to-be and passing-away: but the substratum of the remaining kinds of change is also, in a certain sense, 'matter', because all these substrata are receptive of 'contrarieties' of some kind.

So much, then, as an answer to the questions (i) whether coming-to-be 'is' or 'is not'—i.e. what are the precise conditions of its occurrence and (ii) what 'alteration' is.

73. After showing why there is a certain absolute generation and a certain qualified generation, the Philosopher here inquires into the difference between generation and alteration.

First, he states his intention (319b6) and says that we must discuss generation and alteration and indicate how they differ, for we have stated above that these are different types of change.

Second, he carries out his intention, at since, then, we must distinguish (319b8; [74]).

First he shows the difference between generation and alteration with respect to that according to which both are changes;

second, with respect to the subject of each, at when the change from contrary (319b31; [79]).

Regarding the first he does two things:

first, he shows the difference between generation and alteration;

second, he removes a difficulty, at if, however, in such cases (319b21; [77]).

About the first he does two things:

first, he shows in what things alteration occurs;

second, in what things generation occurs, at but when nothing perceptible (319b14; [75]).

74. With respect to the first (319b8) he supposes two things.

The first is that the subject is one thing and the passion which is apt to be said of a subject is another, just as in the case of substance and accident.

The second is that change occurs in both of these; for sometimes the change is in the very substance of the subject and sometimes in the accidents.

With these suppositions in mind he says that it is alteration when the same perceptible subject remains, i.e., when, with no change having taken place in the substance, a change occurs in its passions, i.e., in its qualities. And it makes no difference whether the change involves contrary extremes or intermediates—for example, whether it is from white to black or from red to pale. He gives two examples: the first is when the body of an animal, while remaining the same, is first healthy and then sick; the second is when bronze or some other metal, while remaining the same, is now round and now angular, or possessing angles.

And it should be noted that the first of these examples pertains to the first species of quality and the second example to the fourth species. Yet the Philosopher proved in Physics VII that there is no motion of alteration in the first and fourth species of quality but only in the third, which is called passion or passible quality—for which reason he perhaps advisedly said that alteration is a change in the passions.

But it should be said that alteration is primarily and per se in the qualities of the third species, through which alteration subsequently occurs also in the other species. For example, by reason of some change within the sphere of hot and cold a man is changed from healthy to sick, or vice versa; and through a change within the sphere of soft and hard a body is brought to some shape.

75. Then, at but when nothing perceptible (319b14), he shows when generation occurs. About this he does two things:

first, he states when there is generation;

second, when there is generation par excellence, at it is a coming-to-be (319b17; [76]).

He says therefore first (319b14) that when a change affects not only the passions but the entire substance of a thing, in so far, namely, as the matter acquires another substantial form so that nothing perceptible remains as though the being in act were the same subject as to number — for example, when from the whole seed, there is generated what is wholly blood, or when from what is wholly air there is generated what is wholly water, without any gatherings or separatings playing a part as Democritus posited—such a change is the generation of one thing and the corruption of another.

76. Then, at it is a coming-to-be (319b17), he explains when there is generation in the highest degree. And he says that according to the third way laid down above and which is taken according to the opinion of many, above all is something said to be generated when the change proceeds from something not easily perceptible to something clearly perceptible, either to touch, which, among the senses, is more gross and material (hence among the people it is according to this sense above all that something is judged as perceptible—in so far as it may be felt), or to the other senses—as, when water is generated from air, there seems to be according to this outlook, generation which is absolute, or when it is corrupted into air there seems to be absolute corruption. For air is only slightly perceptible, both because it is so rarified and because it has no excelling active quality, but only a passive one, namely, moistness; while in fire, which is more rarified than air, an active quality, heat, does excel. But water is both denser than air and there excels in it an active quality, coldness; earth, finally, is the densest of all the elements.

77. Then, at if, however, in such cases (319b21), he removes a difficulty. For since he had said that the subject remains when a change has taken place with respect to its passions, someone could believe that in the case of everything with respect to which something is changed while something other remains, that which is changed is a passion of that which remains.

But he excludes this when he says that in those bodies that are reciprocally changed one from the other, sometimes there remains some one and the same passion in the generated and in the corrupted thing, as when from air is produced water — for both are diaphanous, i.e., transparent, or cold (although air is not cold by nature but accidentally); yet this does not mean that the other thing, in which the change takes place, namely, the air or the water, is a passion of that which remains, namely, the diaphanous or the cold. If what we now say were not so, it would follow that when water comes to be from air, it would be alteration; for we always see that when that which is changed is a passion of what remains, we have alteration, but when that which is changed is not a passion of what remains, it is generation.

He shows this by means of an example. We say that musical man has been corrupted when man loses the habit of music, at which time unmusical man, i.e., man having the privation of music is generated. The reason for this is that music is not a passion of musical man, since it is of its notion; likewise, unmusical is of the notion of unmusical man. Hence musical man does not remain; but the same numerical man does remain. Therefore, if music and lack of music were not passions of this, i.e., of man, but were part of his notion, then the change of musical and unmusical would constitute the generation of one thing and the corruption of another. But because this is not so, therefore music and lack of music are passions of man. But there is a generation and corruption of musical and unmusical man; and because man remains, as is evident, it follows that music is a passion of that which remains [namely, man]. Therefore alteration occurs with respect to such, i.e., the passions of things that are permanent. If, therefore, water and air were passions of the transparent, as of something permanent, it would follow that the change of water from air would be alteration.

78. But there is a problem as to whether the same numerical passion which is at one extreme of a set of contraries could exist in the generated and in the corrupted, as was said above. For if it does not remain the same, then the transition into each other of things that are similar will not be easier, since on both sides it will be necessary to remove everything. Similarly, it seems to follow that like is destroyed by like, for the generator destroys that which previously was present. But if one supposes the same numerical passion to remain, it follows that even though that which was prior, namely, the subject, has been removed, that which was subsequent, namely, the passion, remains. Moreover, the same numerical accident would be in two subjects.

It should be answered, therefore, that the same numerical passion does not remain, but that what existed previously is corrupted ear accidens with the corruption of the subject, when the form which was the principle of that accident departed, and that a similar accident comes, following on the newly-arriving form. And because, with respect to this accident, there was no conflict between agent and patient, the change was easier. Nor is it unacceptable for like to destroy like ear accidens, i.e., by reason of corrupting the subject or matter—this is the same way in—which a larger flame consumes a smaller.

79. Then, at when the change from contrary (319b31), he shows, from the side of the subject, how generation differs from alteration and from other changes.

First, he shows how all of them are related to the subject which is a being in act;

second, how related to the subject which is a being in potency, at "matter," in the most proper sense (320a2; [81]).

He says therefore first (319b31) that, as was said, alteration is according to the passions of something that remains. And this same thing occurs in other changes, which take place with respect to accidents which occur to a subject existing in act. When, therefore, a change is from contrary to contrary according to quantity—for example, from large to small, or vice versa—we have growth or decrease of the same permanent subject, since quantity occurs to a subject existing in act. But when the change is with respect to contrariety of place—for example, up or down—it is latio, i.e., local motion, of the same remaining body, since where accrues to a body existing in act. When the change is with respect to a contrariety in passions (i.e., primarily in passible qualities, and in other qualities as a consequence), we have alteration of the same permanent being, because quality too accrues to a subject existing in act. But when nothing remains existing in act, of which that which is changed might be a passion or some accident, it is universally generation and corruption, since the substantial form, with respect to which generation and corruption occur, does not accrue to a subject existing in act.

80. Hence it is evident that the opinion is false which Avicebron handed down in the book Font of Life, namely, that in matter there is an order of forms, in the sense that first matter acquires a form making it a substance, and then another that makes it a body, and then another which makes it living body, and so on. For since it is one and the same thing to constitute a substance and to make a "this something," which pertains to particular substance, it would follow that the first form, which constitutes the substance, would also make it a "this something, which is a subject existing in act. Consequently, the subsequent forms would accrue to a permanent subject, and with respect to them there would be alteration rather than generation, according to the doctrine which Aristotle here transmits.

Therefore one should say, as was said above, that substantial forms differ according to more and less perfect. But the more perfect can do all that the less perfect can do, and more; hence the more perfect form that makes a thing "living" can also make it "body," as does the more imperfect form of non-living body. Consequently, no substantial form accrues to a subject existing in act, nor does it presuppose some other common form really distinct from it, which would be the object of natural philosophy, but only one distinct according to reason, and which pertains to the consideration of logic.

81. Then, at "matter," in the most proper sense (320a2), he compares all the above-mentioned changes to the subject which is only being in potency. And he says that it is above all hyle, or first matter, which is the proper subject of generation and corruption, because, as has been said, it immediately underlies the substantial forms, which come and go by generation and corruption. But in a certain sense, i.e., consequently and mediately, it also underlies all the other changes, because all the subjects of the other changes are susceptible of certain contrarieties which are reduced to the first contrariety, which is that of form and privation, whose subject is first matter, as is said in Physics I. And therefore all the other subjects partake in some sense of first matter in so far as they are composed of matter and form.

In summary (320a5) he concludes that so much, then, has been determined concerning absolute generation, as to whether it exists or not, and what are the precise conditions of its occurrence, and in a like manner concerning alteration.