Lecture 16 — How growth takes place. Its difference from generation.

The whole, however, has become larger. And this increase is due (a) on the one hand to the accession of something, which is called 'food' and is said to be 'contrary' to flesh, but (b) on the other hand to the transformation of this food into the same form as that of flesh as if, e.g. 'moist' were to accede to 'dry' and, having acceded, were to be transformed and to become 'dry'. For in one sense 'Like grows by Like', but in another sense 'Unlike grows by Unlike'.

One might discuss what must be the character of that 'whereby' a thing grows. Clearly it must be potentially that which is growing—potentially flesh, e.g. if it is flesh that is growing. Actually, therefore, it must be 'other' than the growing thing. This 'actual other', then, has passed-away and come-to-be flesh.

But it has not been transformed into flesh alone by itself (for that would have been a coming-to-be, not a growth): on the contrary, it is the growing thing which has come-to-be flesh (and grown) by the food. In what way, then, has the food been modified by the growing thing? Perhaps we should say that it has been 'mixed' with it, as if one were to pour water into wine and the wine were able to convert the new ingredient into wine. And as fire lays hold of the inflammable, so the active principle of growth, dwelling in the growing thing that which is actually flesh), lays hold of an acceding food which is potentially flesh and converts it into actual flesh. The acceding food, therefore, must be together with the growing thing: for if it were apart from it, the change would be a coming-to-be. For it is possible to produce fire by piling logs on to the already burning fire. That is 'growth'. But when the logs themselves are set on fire, that is 'coming-to-be'.

110. Having solved the questions which concerned the nature of growth, the Philosopher here determines the manner of growth.

First, he determines how growth takes place;

second, how diminution takes place, at the form of which (322a28; [118]).

About the first he does two things:

first, he shows how that which comes is related to that which is increased by its coming;

second, he compares growth to the other operations of the vegetative soul, at one might discuss (322a4; [111]).

He says therefore first (321b35) that after settling the question of the parts of that which grows, namely, whether each part grows or not, it is now plain that the whole becomes larger as a result of something coming to it—for example, food. Now although that which comes is in the beginning contrary to what it comes to, yet later it is converted into the same species. For example, if something originally moist comes to what is dry, it is changed and made dry. Consequently it is in a sense true to say that like is increased by like; but it is also in a sense true to say that something is increased by what is unlike, For that by which something is increased is in the beginning unlike but at the end like, as has been said.

111. Then, at one might discuss (322a4), he compares growth with the other operations of the soul, whose operations are three, as is stated in On the Soul II, namely, generation, nutrition and growth.

First, therefore, he compares growth to generation;

second, to nutrition, at "quantum-in-general" (322a16; [113]).

About the first he does two things:

first, he shows how growth and generation are alike;

second, how they differ, at but it has not been transformed (322a6; [112]).

Therefore (322a4) he asks, concerning the first, of what sort, i.e., of what form, must that be by which something is increased. And he concludes that it is plain from the foregoing that that by which something is increased is in potency to what is increased; for example, if flesh is what is increased, that by which it is increased must be flesh in potency, because, as was said above, that by which it is increased must be unlike in the beginning, but like at the end. And since nothing is in potency to one thing without being something else in act, then that by which flesh is increased and which is in potency to flesh, must be in act something other than flesh, e.g., bread. But what is something in act does not become something other but by the corruption of the former and the generation of the latter. Therefore growth must take place following the corruption of that which previously existed in act, e.g., bread, and the generation of that which grows, e.g., flesh. Thus it is plain that, in some manner, generation concurs in growth.

112. Then, at but it has not been transformed (322a6), he shows how growth and generation differ. And he says that, since growth involves a certain generation of flesh, but growth is different from generation, it follows that there is not generation of a thing according to itself, i.e., separately, when something is thus generated (for that would make it generation and not growth). Rather flesh must be generated into the flesh which grows. Consequently that which becomes flesh in the growing thing, undergoes, in so far, namely, as it is made like that which is increased, and by means of this, namely, of what has undergone and been changed, that to which it is added, or the whole compound, is increased. A similar situation occurs when water is poured into pre-existing wine in such a way that the wine, by its power, is able to convert the added water into its own nature; in such a case there is said to be an increase of wine, but not generation. But when some liquid is converted into wine according to itself, for example, the juice of grapes, there is then generation of wine.

He gives another example, that of fire which burns combustible material added to it. For that is what happens in a growing thing, which is flesh in act, and whose augmentative power makes that which comes, and which is flesh in potency, to be flesh in act—in such a way, however, that it is with the pre-existing flesh. For if, out of something potentially flesh, flesh were produced separately, there would be generation of flesh, not growth. This is what happens when, by the power of the seed, the menstrual blood is changed into flesh. This also happens in the case of fire: sometimes pieces of wood are ignited upon being added to an already-existing fire—and this is an increase of fire; but sometimes the pieces of wood are ignited apart, not added to other burning pieces—then there is generation.