Lecture 8 — Generation by art and by chance

However, someone might raise the question of why some things come to be both by art and by chance, like health, while others do not, like a house.

And the reason is that, in some of these, the matter, which is the principle of generation in the making and producing of everything which comes to be by art, and in which some part of the thing made is present, the matter of these, I say, is such that it can set itself in motion, whereas the matters of others cannot.

And of the former kind, some can set themselves in motion in a special way, and some cannot.

For many things can move themselves but not in a special way, as in dancing. Those things, then, whose matter is such—for instance, stones—cannot be moved except by something else. Yet, in another way, they can move themselves, as in the case of fire. For this reason, some things will not exist apart from something that has art, while others will; for they will be moved either by those things that do not have art or from a part.

And it is evident from what has been said that, in a sense all things come from something which is univocal (as natural things), or from something which is univocal in part (as a house comes from a house, or by means of mind, since art is a form), or from a part or from something having a part, unless it comes to be accidentally.

For the first and proper cause of the production of anything is a part of the thing produced. For the heat in the motion produces heat in the body; and this is either health or a part, or some part of health or health itself follows from it. Hence it is said to cause health, because it makes health, which follows from it, and heat occurs. Hence, just as in syllogisms the basis of everything is substance (for a syllogism proceeds from the whatness of a thing), so too, in this case, processes of generation proceed from it.

And those things that are constituted by nature are similar to these, for the seed produces something in the same way as things that operate by art.

For it contains the form potentially, and that from which the seed comes [and the thing which it generates] are in a sense univocal, for it is not necessary to inquire about all things in the same way as we do when we say that a man comes from a man; for a woman also comes from a man. Hence a mule does not come from a mule, unless there should be some defect.

And whatever things arise by chance, as some artificial things do, are those whose matter can be moved by itself by the very motion by which the seed moves. But those things whose matter does not possess this capacity cannot be generated in any other way than by the agents themselves.

Now, it is not only with reference to substance that our argument proves that the species does not come to be, but the common reasoning also applies in a similar way to all the primary genera, such as quantity, quality, and the other categories.

For a brazen sphere as such comes to be, but not the sphere or the bronze; but if it does come to be, it comes to be in the bronze (because it is always necessary that the form and the matter preexist). And this must also be the case with the quiddity, with quality, with quantity, and also with the other categories.

For quality does not come to be, but wood of such a quality; and quantity does not come to be, but so much wood or so large an animal.

But, from these remarks, it is possible to learn a property of substance, namely, that there must always preexist another actual substance which produces it. For example, an animal must preexist if an animal is generated. But quantity and quality must preexist only potentially.

1436. Having shown that separate forms are not the cause of generation in these lower bodies, the Philosopher now clears up certain things that could be regarded as problems relating to the points already established.

This is divided into three parts insofar as there are three problems which he intends to clear up.

The second part (1034a21; [1443]) begins where he says, and it is evident;

the third (1034b7; [1458]) begins at the words, now, it is not only.

In regard to the first, he does two things.

First (1034a9; [1436]), he states the problem.

Second (1034a10; [1437]), he solves it, at and the reason.

Now the first problem stems from a statement which he had made above (1032b30; [1412]) to the effect that, when the principle of health is the form in the mind, health is then a result of art; but when health is not a result of this principle, but only of the act of heating, health then comes about by chance (such as when health happens to result from a vigorous rubbing). But this cannot be true of everything that comes to be by art, for a house is never produced by any principle except the form of a house in the mind, and thus it will always come to be by art and never by chance. Hence the problem is why some things, such as health, sometimes come to be by art and sometimes by chance, while others, like a house, come to be only by art, and never by chance.

1437. And the reason (1034a10). He then solves the problem. He says that the reason for the above-mentioned difference in the case of artificial things lies in the fact that the matter from which generation begins, inasmuch as it is the basis of the making and producing any of the things that come about by art, is such as to contain some part of the thing generated. For the matter must have some aptitude for form, because not any artifact can be produced from any matter, but each from some definite matter. For example, a saw is not produced from wool, but from iron. Hence the aptitude itself of the artifact for a form, which is in the matter, is already some part of the artifact which is in the matter, because without this aptitude, the artifact cannot exist. For instance, there cannot be a saw without hardness, by which the iron is disposed for the form of a saw.

1438. But this part is found in matter in two ways: sometimes in such a way that the matter can move itself by this part (that is, by the part of the form existing within it), and sometimes not.

For example, in the case of the human body, which is the matter of health, there is an active power by which the body can heal itself, but in the case of stones and timbers, there is no active power by which the matter can be moved to receive the form of a house.

1439. And, if the matter can be so moved to receive a form by a part of the form which exists in it, this can occur in two ways.

For sometimes it can be moved by an intrinsic principle, which is the part mentioned above, in the same way in which it is moved by art, as occurs in the restoration of health. For the nature of the human body acts in the same way with regard to health as art does.

But sometimes the matter cannot be moved by an intrinsic principle in the same way in which it is moved by art, although it can be moved by itself in some way. For there are many things that can be moved by themselves, but not in the same way in which they are moved by art, as is clear in the case of dancing. For men who do not have the art of dancing can move about, but not in the way in which those men do who have this art.

1440. Therefore, those artificial things that have this kind of nature, as stones are the matter of a house, cannot set themselves in motion, for they cannot be moved except by something else. This is true not only of artificial things but also of natural ones, for in this way, too, the matter of fire cannot be moved to receive the form of fire unless it is moved by something else. And it is for this reason that the form of fire is generated only by something else.

For this reason, some artificial things cannot come to be unless there is something that has art—that is, those which do not have in their matter any principle that can move their matter to receive a form, or those which cannot cause motion in the way in which art does.

1441. And those things that can be moved by some extrinsic principle that is not possessed of art can both be and come to be without the intervention of art; for the matters of these are moved by things that do not possess art. He makes this clear in two ways.

First, by pointing out that this can happen insofar as they can be moved by certain other extrinsic principles that do not have art; as a tree can be planted even by someone who does not have the art of planting.

Second, when the matter is moved from a part, namely, by some intrinsic principle, which is some part of the form—for example, when health is restored to the human body by some intrinsic principle which is a part of the form.

1442. Now it must be noted that some persons, because of the words which are used here, claim that, in every natural generation, the matter contains some active principle which is the form preexisting potentially in the matter and a kind of beginning of form; thus it is called a part of the form. And they first try to establish this from the statements made here, for Aristotle seems to say here that those things whose matter contains no active principle are produced by art alone. Therefore, they think that some active principle must be present in the matter of things that are generated by nature.

Second, they try to establish this from the fact that every motion whose principle is not intrinsic to the thing moved, but extrinsic to it, is a violent motion and not a natural one. For if there were no active principle in the matter of those things that are generated by nature, the process of generation of these things would not be natural, but violent. In other words, there would be no difference between artificial generations and natural ones.

And when one argues against them that, if the generation of those things that come about by nature is from an intrinsic principle, such things do not therefore stand in need of any extrinsic generator, they answer as follows. Just as an intrinsic principle is not a perfect form, but a kind of beginning of form, neither is it a perfect active principle in the sense that it can act of itself so as to bring about generation; but it bears some likeness to an active power inasmuch as it cooperates with an extrinsic agent. For if the mobile object contributes nothing to the motion produced by an external agent, the motion is violent, because violence exists when the thing undergoing the change is moved by an extrinsic principle and does not itself contribute anything to the change, as is stated in Ethics 3.

Now this opinion seems to resemble the one expressed by those who claim that forms lie hidden, for, since a thing acts only insofar as it is actual, if the parts or beginnings of the forms which exist in matter have some active power, it follows that they are actual to some degree. This is to maintain that forms lie hidden. Furthermore, since being is prior to action, a form cannot be understood to act before it actually exists.

Therefore, it must be said that, just as living things alone are found to move themselves locally, whereas other things are moved by an extrinsic principle—that is, either by one which generates or by one which removes some obstacle, as is stated in Physics 8—so too, only living things are found to move themselves with the other motions. This is because they are found to have different parts, one of which can be a mover and the other something moved; and this must be true of everything that moves itself, as is proved in Physics 8. Hence, in the generation of living things, we find an intrinsic efficient principle, which is the formative power in the seed. And just as living things have a power of growth, which is responsible for the motion of increase and decrease, in a similar fashion they have an intrinsic motive principle responsible for the qualitative change of being healed. For, since the heart is not subject to disease, the natural power which is present in it, as in something healthy, changes the whole body to a state of health.

Hence, the Philosopher is speaking here of such matter as has an efficient principle within itself, and not of inanimate things. This is clear from the fact that he compares the matter of fire with the matter of a house in this respect: both are moved to receive their form by an extrinsic principle. It does not follow, however, that the process whereby inanimate bodies are generated is not natural, for in order to have natural motion, it is not necessary that the principle of motion present in the thing moved should always be an active and formal principle; but sometimes it is passive and material. Hence, in Physics 2, nature is distinguished into matter and form. And the natural generation of simple bodies is said to proceed from this principle, as the Commentator says in his commentary on Physics 2. Yet there is a difference between the matter of natural things and that of things made by art, because, in the matter of natural things, there is a natural aptitude for form, and this can be brought to act by a natural agent, but this does not occur in the matter of things made by art.

1443. And it is evident (1034a21). Then he clears up the second problem which could arise from the foregoing discussion, for he had said above (1033b29; [1432]) that everything which is generated is generated by something having a similar form. Now, this does not apply in the same way to all things, and therefore he intends here to clarify how this applies in a different way to different things. In regard to this, he does two things.

First, he distinguishes the different ways in which the thing generated is like the thing which generates it.

Second (1034a25; [1448]), he explains these ways, at for the first.

With regard to the first (1034a21), it must be noted that everything which is generated by something is generated by it either properly or accidentally. Now, whatever is generated by something accidentally is not generated by it according as it is a thing of some special kind. Hence, in the generator, there does not have to be any likeness of the thing generated. For example, the discovery of a treasure has no likeness in him who, when he digs in order to plant something, discovers the treasure accidentally. But a generator in the proper sense generates something of the same kind as itself. Hence, in a proper generator, the likeness of the thing generated must exist in some way.

1444. But this comes about in three ways.

First, when the form of the thing generated preexists in the generator according to the same mode of being, and in a similar matter, as when fire generates fire or man begets man. This type of generation is wholly univocal.

1445. Second, when the form of the thing generated preexists in the generator neither according to the same mode of being nor in a substance of the same kind. For example, the form of a house preexists in the builder not with the material being which it has in the stones and timbers, but with the immaterial being which it has in the mind of the builder. This type of generation is partly univocal, from the standpoint of form, and partly equivocal, from the standpoint of the being of the form in the subject.

1446. Third, when the whole form of the thing generated does not preexist in the generator, but only some part of it or a part of a part. Thus, in the medicine which has been heated there preexists the heat which is a part of health, or something leading to a part of health. This type of generation is not univocal in any way.

1447. Hence he says, it is evident from what has been said that, in a sense, all things come from something which is totally univocal, like natural things. For example, fire comes from fire, and a man from a man.

Or it comes from something which is univocal in part, in reference to the form, and equivocal in part, in reference to the being which the form has in the subject. For example, a house comes from the house which is the art in the builder, or by means of mind, or by a habit of art; for the building art is the form of the house.

Or in a third way, some things come from the form preexisting in the generator, or from the generator himself who possesses a part of the above-mentioned form. For the process of generation can be said to be a result either of the form or of a part of the form, or of something having the form or a part of the form; but it comes from something having the form as from a generator, and from the form or a part of the form as from something by which the generator generates.

For it is not the form that generates or acts, but the thing having the form generates and acts by means of it. By this I mean that a thing is generated by something like itself in the ways mentioned above, unless it comes about in an accidental way; for then it is not necessary that any likeness of this kind should be observed, as has been explained [1443].

1448. For the first (1034a25). Here he explains the ways mentioned above in which one thing comes from something else.

He does this first in the case of artificial things;

second (1034a33; [1451]), in the case of natural ones, at and those things that.

He accordingly first says (1034a25) that the thing produced must come from some part, because the first and proper cause of the production of anything produced is the part of it which preexists in the one producing it, and which is either the form itself of the producer or a part of the form. For when heat is caused by motion, heat is present in a sense in the motion itself, as in an active power. For the power of causing heat which is in the motion is itself something belonging to the genus of heat, and the heat which is present virtually in the motion causes the heat in the body not by a univocal generation, but by an equivocal one. For the heat in the motion and that in the heated body are not of exactly the same nature. And this, namely, the heat, is either health itself or a part of health, or some part of health or health itself follows from it.

1449. Now, by these four alternatives which he gives he wants us to understand the four modes in which the form of the thing causing generation can be referred to the form of the thing generated.

The first of these is found when the form of the thing generated is totally in the thing which causes generation, as the form of a house is in the mind of the architect, and the form of the fire which is generated is in the fire which generates it.

The second mode is found when a part of the form of the thing generated is in the thing causing generation, as when a hot medicine restores health by heating, for the heat produced in the one who is being healed is a part of health.

The third mode is found when part of the form is in the thing causing generation not actually, but virtually, as when motion restores health by heating, for heat is present in the motion virtually but not actually.

The fourth mode is found when the whole form itself is present virtually but not actually in the thing which causes generation—for example, the form of numbness is in the eel which makes the hand numb. And it is similar in the case of other things that act by means of the whole form.

Therefore, he refers to the first mode by the words either health; to the second mode by the words or a part; to the third by the words or some part of health follows from it; and to the fourth by the words or health itself.

And, since motion causes the heat from which health follows, for this reason too motion is said to cause health, because it makes health, which follows from it, or health occurs. Or better, a result of motion, namely, heat, causes health, which follows from it and occurs.

1450. Hence, it is evident that, just as in syllogisms the basis of all demonstrations is substance, that is, the whatness (for demonstrative syllogisms proceed from the whatness of a thing, since the middle term in demonstrations is a definition), so too, in this case, namely, in matters of operation, processes of generation proceed from the quiddity. In this statement, the likeness of the speculative intellect to the practical intellect is shown, for just as the speculative intellect proceeds to demonstrate the properties of subjects from a study of their quiddity, in a similar fashion, the intellect proceeds from the form of the work, which is its quiddity, as was stated above.

1451. And those things (1034a33). Here he explains his statement about artificial things in their application to natural things. He says that those things that are constituted by nature are similar to those which come to be by art. The seed acts for the purpose of generating, and this is what happens in the case of things that come to be by art; for just as an architect is not a house actually and does not possess the form which constitutes a house actually, but only potentially, so too the seed is not an animal actually, nor does it possess a soul actually, which is the form of an animal, but only potentially. For in the seed, there is a formative power which is related to the matter of the thing conceived in the same way that the form of the house in the mind of the builder is related to the stones and timber.

But there is this difference: the form of an art is wholly extrinsic to the stones and timbers, but the power of the seed is present in the seed itself.

1452. Now, although the generation of an animal from seed does not proceed from the seed as from something univocal, since the seed is not an animal, still that from which the seed comes is in some measure univocal with the thing which comes from it, for the seed comes from an animal. And in this respect, natural generation bears no likeness to artificial generation, for it is not necessary for the form of the house in the mind of the architect to come from a house, although this sometimes happens, as when someone makes a plan of one house from that of another. But it is always necessary for seed to come from an animal.

1453. Moreover, he explains what he meant by the phrase in a sense univocal, because, in natural generations, it is not necessary that there should always be univocity in every respect, as there is when a man is said to come from a man, for a woman also comes from a man as an agent. And a mule does not come from a mule, but from a horse or an ass, and in this case, there is some likeness, as he said above (1033b29; [1433]).

Further, since he had said that there must be univocity to some degree because of that from which the seed comes, he adds that this must be understood unless there should be some defect, that is, unless there is some shortcoming of natural power in the seed. For then the generator produces something which is not similar to itself, as is evident in the birth of monsters.

1454. And, just as in those artificial things, some come to be not only by art but also by chance, when the matter can be moved by itself by the same motion according to which it is moved by art (but when it cannot be moved in this way, then that which comes to be by art cannot be produced by anything else than art), so too in this case, some things can come to be by chance and without seed whose matter can be moved by itself in this way by the very motion by which the seed moves, that is, with the aim of generating an animal. This is evident in the case of those things that are generated from decay and are said in one sense to be a result of chance, and in another not, as was explained above [1403]. But those things whose matter cannot be moved by itself by that very motion by which the seed is moved are incapable of being generated in another way than from their own seed; this is evident in the case of man and horse and other perfect animals.

Now, it is clear from what is said here that not all animals can be generated both from seed and without seed, as Avicenna claims, but neither [is it the case] that none can be generated in both ways, as Averroes claims.

1455. Now it must be observed that, from what has been said here, it is possible to solve the problems facing those who claim that the forms generated in these lower bodies do not derive their being from natural generators, but from forms which exist apart from matter. For they seem to maintain this position chiefly because of those living things that are generated from decay, whose forms do not seem to come from anything that is similar to them in form.

And again, since even in animals which are generated from seed the active power of generation, which is in the seed, is not a soul, they said that the soul of the animal which is generated cannot come from the seed. And they proceed to argue thus because they think that no active principle of generation is found in these lower bodies except heat and cold, which are accidental forms, and it does not seem that substantial forms can be generated by means of these.

Nor does it seem that the argument which the Philosopher used against those who posited separate exemplars holds in all cases, such that the forms in things causing generation are sufficient to account for the likeness of form in the things that are generated.

1456. But all these difficulties are solved by the text of Aristotle if it is examined carefully. For it is said in the text that the active power in the seed, even though it is not an animal actually, is nevertheless an animal virtually. Hence, just as the form of a house in matter can come from the form of house in the mind, so too a complete soul can come from the power in the seed, exclusive of the intellect, which is from an extrinsic principle, as is said in On Animals 16. And this is true inasmuch as the power in the seed comes from a complete soul by whose power it acts, for intermediate principles act by virtue of primary principles.

1457. Now, in the matter of those things that are generated from decay, there also exists a principle which is similar to the active power in the seed, by which the soul of such animals is caused. And, just as the power in the seed comes from the complete soul of the animal and from the power of a celestial body, in a similar fashion, the power of generating an animal which exists in decayed matter is from a celestial body alone, in which all forms of things that are generated are present virtually as in their active principle. And, even though active qualities are operative, they do not act by their own power, but by virtue of their substantial forms to which they are related as instruments, as it is said in On the Soul 2 that the heat of fire is like an instrument of the nutritive soul.

1458. Now, it is not only (1034b7). Then he clears up the third problem that could arise from his remarks, for he had proved above that it is not forms which are generated, but composite things, and someone could be puzzled as to whether this is true only of substantial forms or also of accidental forms. So his aim here is to meet this problem, and therefore he does two things.

First, he shows that this is true of both types of forms. He says that the argument given above with reference to substance, that is, the category of substance, not only shows that the species, or form, does not come to be, but is common in a similar way to all the primary genera, or to the categories, such as quantity, quality, and so on. For a brazen sphere as such comes to be, that is, a composite such as a brazen sphere, but not the sphere, that is, what has the character of a form, or the bronze, that is, what has the character of matter.

And if a sphere does come to be in some manner of speaking, it does not come to be in itself, but comes to be in bronze. For in order for generation to take place, the matter and the form must preexist, as was shown above (1032a13–1032a20; [1383–88]). Thus, it is a brazen sphere as such, namely, the composite, which comes to be, and this must also be the case with the quiddity, that is, the category of substance, and with quality and quantity, and also with the other categories. For quality does not come to be, that is, quality itself, but this whole which is wood of such a quality, nor does quantity come to be, that is, quantity itself, but so much wood or so large an animal.

1459. But, from these remarks (1034b16). He shows what the difference is between substance and accidents. He says that we must take this characteristic to be a property of substance as compared with accidents: when a substance is generated, there must always exist another substance which causes its generation. For example, in the case of animals generated from seed, if an animal is generated, another animal which generates it must preexist. But in the case of quantity and quality and the other accidents, it is not necessary that these preexist actually, but only potentially, and this is the material principle and subject of motion. For the active principle of a substance can only be a substance, but the active principle of accidents can be something which is not an accident—namely, a substance.