Commentaria in Summam contra Gentiles, Liber II

As to the fourth¹, Saint Thomas answers the arguments set forth above². In this matter he does two things: first, he sets forth a most beautiful doctrine concerning the process of generation; second, he answers each argument individually³.

I. As to the first, he states it summarily in seven points.

The first point is that the opinion of those who say that the works of life which appear in the embryo before its final completion do not come from any soul or from a power existing in it, but from the soul of the mother, is false. First, because then the embryo would not be an animal. — Then, because the operations of life do not proceed from an extrinsic principle (namely, immediately), but from an intrinsic one: as appears in nutrition, by which what is nourished assimilates nourishment to itself, and much more evidently in the operations of sense.

The second argument is that it is false that the soul, according to its complete essence, is in the seed from the beginning, while its operations do not appear because of the lack of organs. First, because the soul is not united to the body as its form unless the body is organized. — Second, because Aristotle, in Book II On the Soul, text 10, says that seed and fruit are in such a way in potency to having life that they cast off the soul. — Third, because then the generation of an animal would be completed in the very separation of the seed: just as in annulose animals two are made from one. And thus it would follow that all the subsequent transmutations would be irrelevant to generation; for the transmutations that follow upon the substantial form are not ordered to the being of the generated thing, but to its well-being. — It would also follow that the rational soul would be divided with the division of the body. — And that from every emission from which conception does not follow, rational souls would be multiplied.

The third is that this opinion is also false which holds that, just as the seed is a body not actually organized but organizable, so the power present in the seed is soul in potency and not in act; and that, once the seed has been sufficiently organized for plant life, the aforementioned power becomes the vegetative soul; then, with more perfect organs, the same becomes sensitive; finally, once the organs are perfectly formed, the same becomes the rational soul—not indeed by an action of the seed's power, but from the action and illumination of an external agent; and that on account of this Aristotle said that intellect comes from without. This opinion is false: first, because then the substantial form would be perfected more and more continuously. — Second, because the substantial form would not be brought into act all at once but successively, and thus generation would be a continuous motion. — Third, because it would follow that the rational soul is mortal. For the rational soul would be the same as the sensible soul, which in the aforementioned process is posited as generated per accidens, and consequently is posited as corruptible along with the corruption of the body. — Nor can it be said that it becomes incorruptible through the external light through which the said soul becomes rational. For nothing arriving formally in a corruptible thing makes it incorruptible by nature ⁴, since the corruptible and incorruptible differ in genus, X Metaphysics, text 26.

Fourth, the aforesaid power, which is founded in the spirit whose seed it contains, brings about the formation of the body by the power of the father's soul, to which generation is principally attributed; not, however, by the power of the soul of the conceived offspring, even after it has a soul, for the conceived does not generate itself but is generated from another; as is evident by running through each of the powers of the soul. For the formation of the body cannot be attributed to the soul of the embryo by reason of the generative power: since that power exercises its operation only when the work of the nutritive and augmentative powers is complete; nor is it ordered to the perfection of the individual itself, but to the preservation of the species. Nor can it be attributed to it by reason of the nutritive power: because in the course of formation the nourishment is led on to a more perfect form and one closer to the likeness of the father, whereas it is not drawn toward the likeness of what preexists, which happens through the work of the nutritive power assimilating the nourishment to the nourished. Nor is it done by the power of the augmentative: since that power concerns change not according to form but only according to quantity. Nor is it done by the power of the sensitive or intellective faculty: as is evident. It remains, therefore, that the formation of the body, especially with respect to its first and principal parts, comes solely from the power of the generating soul ⁵.

Fifth, this formative power remains in the aforementioned spirit from the beginning of formation until the end ⁶; yet the species of what is formed does not remain the same, since it has diverse forms successively until completion. For although the generation of simple bodies does not proceed according to an order, because each of them has its form immediately from prime matter, nevertheless in the generation of other things there must be an order of generations, on account of the many intermediate forms between the first form of the element and the last to which generation is ordered ⁷.

Sixth, it is not unfitting if something among the intermediates is generated and immediately afterward corrupted: for those things, as lacking a complete species, are not generated so as to endure, but so that through them one may arrive at what is generated last. — Nor is it strange that the whole transmutation of generation should not be continuous: for this happens also in the whole of alteration and the whole of augmentation ⁸; and only local motion is truly continuous, VIII Physics, text 64 and below.

Seventh is that, the nobler any form is and the more distant it is from the form of an element, the more intermediate forms there must be, and more generations and corruptions. And therefore in the generation of man, the vegetative soul, which is first present in the embryo while it lives the life of a plant, is corrupted, and a more perfect soul succeeds it, which is at once nutritive and sensitive, and then the embryo lives the life of an animal. But when this is corrupted, the rational soul succeeds from without, not by the power of the seed, as did the preceding ones.

II. Concerning the third statement, it must be noted that what is corruptible by nature cannot by nature become incorruptible, as though the corruptible were changed into the incorruptible. For since the corruptible and the incorruptible differ in genus, one cannot be changed into the other unless there be a change in genus. Consequently, nothing corruptible by nature, remaining the same in substance and unaltered in genus, can become incorruptible by nature. Yet what is corruptible by nature can, by a supernatural gift, be made incorruptible: so that the same thing will be corruptible and incorruptible—corruptible by nature, but incorruptible by grace or by some supernatural gift preventing it from corruption, as is the case in the bodies of the blessed. On this account Saint Thomas, so as to preserve himself from the incorruptible through a supernatural gift, did not say absolutely that nothing arriving formally in a corruptible thing makes it incorruptible, but that it does not make it incorruptible by nature. And thus, if the sensitive soul, which is corruptible by nature, were to become rational through a supervening light, the rational soul could not become incorruptible by nature, but would remain naturally mortal and corruptible as before.

III. Concerning the fourth statement, where it is concluded that the formation of the body, especially as regards the first and principal parts, is solely by the power of the generating soul, note that Saint Thomas specified the principal and first parts for this reason: because, as he himself says in the First Part, in the question cited ⁹, a. 1, ad 4, once the sensitive soul has been produced in the generated offspring as regards some principal part, that sensitive soul of the offspring then already begins to work toward the completion of its own body by way of nutrition and growth. And thus it is clear that certain parts arriving secondarily can be brought about by the power of the soul of the offspring, while the principal parts, such as the heart, the brain, and the like, are brought about by the power of the generating soul.

IV. Concerning the fifth statement, a twofold doubt arises. The first ¹⁰ concerns what is said there: the formative power remains in the spirit from the beginning of formation until the end. For it seems that Saint Thomas wishes to say that such a power, once formation is finished, does not endure, but endures only up to the completion of the formation. Yet the opposite of this is found in Potentia q. III, a. 9, ad 16, where it is said that the formative virtue which is in the seed at the beginning remains even when the rational soul arrives, just as the spirits, into which almost the whole substance of the sperm is converted, remain.

2. According to ¹¹ it concerns what is said: since in the generation of other bodies there must be an order of generations, on account of the many intermediate forms between the first form of the element and the ultimate form to which generation is ordered. For from this it follows that matter, once stripped of one form, cannot receive any form whatever without order; rather it is necessary that it receive one before another in an orderly and gradual manner. But Saint Thomas says the opposite expressly at V Physics ¹², where, showing how there is no contrariety in substance, he says that matter, once stripped of one form, can receive various forms without order.

The doubt is also strengthened. For it was shown above ¹³ that any substantial form, speaking absolutely, is united immediately to prime matter. Therefore matter can receive through generation any form whatsoever without order. — The consequence is proved: because here St. Thomas assigns the reason why the generation of simple bodies does not proceed in an orderly way, namely, that each of them has a form immediate to prime matter.

V. To the first of these it is answered that Saint Thomas expressly holds, in the First Part, where above ¹⁴, that the active power which was in the seed ceases to be when the seed ceases and the spirit contained in it vanishes: for it is not possible for a power to remain one in number when its subject is destroyed, since an accident can neither subsist of itself nor pass from subject to subject. But what is said in De Potentia etc., namely that it remains, is understood not as remaining the same in number, but in its like. This is clear from two considerations. First, because he assigns the reason for this permanence from the fact that the spirits into which nearly the whole substance of the semen is converted, remain. But it is evident that the substance of the semen is not converted into those same spirits in number which were there before, but into similar ones. And thus a power indeed remains similar to the prior one; yet the prior one need not remain the same in number. — Second, because he confirms the same by the example of heat, which was a disposition toward the form of fire, and which remains when the form of fire arrives. But it is manifest that the heat which preceded the form of fire does not remain the same in number, since with the arrival of the form of fire the subject in which it was is corrupted; rather there remains a heat similar according to species. — It must therefore be said that the formative power remains in its like, but not the same in number. And that which was before formative of the body, as is said there, becomes afterward the same in species, governing the body.

VI. For the clarification of the second doubt ¹⁵, one must first note, from the teaching of St. Thomas on the Spirits, a. 3, ad 20, that matter, considered in itself and without qualification, is indifferent to all forms: namely, because according to its substance it is not determined to one form more than to another, but is receptive of each by its own nature. But when it is considered as perfected by some disposition from the power of an agent, it does not regard all forms indifferently, but certain ones determinately. For there are some forms having among themselves an order with respect to generation, such that they are naturally suited to succeed one another immediately through generation. And therefore, while matter is stripped of one of them, it cannot receive any form whatever indeterminately, but only that which is naturally suited to succeed immediately the prior form, which had been introduced by the agent as a disposition toward a further form: just as, because the form of blood has an immediate order in the generation of an animal to the form of semen, therefore while matter is stripped of the form of semen, it receives no other form immediately than the form of blood.

It must be noted, second, that although matter considered in itself and nakedly is indifferent to all forms, yet as it is disposed by some form by an agent it is not indifferent to all forms, but regards certain ones determinately. Nevertheless, it has one order toward the forms of the elements and another toward the more perfect forms. For, since the forms of the elements hold the lowest grade among forms, no other form of imperfection mediates between prime matter and the forms of the elements, as one that by its imperfection would approach more closely to the nature of matter; and therefore Saint Thomas says in this place that each of the elements has a form immediate to prime matter. But the forms of a higher grade and order, because beneath them in the order of nature lie forms of lower order and grade—and the lower the order of imperfection of a form, the closer it approaches to the nature of matter, since the more something recedes from act and perfection, the more it approaches potency—therefore the forms that are above the elements are not immediate to prime matter according to the order of nature, but the forms of the elements mediate between them and matter; and the higher the order and grade to which a form pertains, the more forms mediate between it and matter in the order of nature. And because nature, in bringing something forth from potency to act, proceeds from the imperfect to the perfect, therefore, when it intends to lead matter to the act of a form of a more perfect order, it first leads it to the act of a form of lesser perfection and nearer to itself according to nature. And this is the reason why, when the form of one element is stripped away, matter can indifferently receive any other form of another element; but when another form is stripped away, it cannot indifferently receive any other form of a superior order, but only a determinate one, namely that which is nearest to the prior form according to grade and order of nature. For in natural generation the less perfect form is introduced by nature as a disposition toward the form placed immediately after it in the order of nature; but in the generation of an element, the form of an element does not serve as a disposition or medium toward the form of another element, since all elemental forms belong to one order, and all regard matter immediately.

It must be noted, third, that it is one thing for a form to be immediate to matter, and another for that form to be united immediately to matter. For when a form is said to be immediate to matter, what is signified is the exclusion of every other form of a lower order and degree from between matter and the form, namely because, according to the order of nature, there is none that by its own imperfection more closely approaches the nature and condition of matter: just as we say that man and animal are immediate, because no other superior species mediates between them which would be prior to man and inferior to animal; on the contrary, however, we say that living thing and man are not immediate, because animal mediates between them in order and degree of nature. — But when a form is said to be united immediately to matter, what is signified is that the form gives esse to matter not through any other intermediary, but through itself, so that every medium is excluded which would have the role of uniting form to matter with respect to esse. Now thus, as was shown above ¹⁶ every substantial form is united immediately to prime matter: because every form of a higher order virtually contains all the other forms of lower orders, and gives to matter whatever the forms of lower orders would give. Yet not every form is immediate to matter in the order of nature, as has been shown: since there are diverse degrees and diverse orders of forms.

It is therefore clear from these considerations that St. Thomas spoke well in holding that in the generation of bodies above the elements there must be a generation ordered through many intermediate forms—namely, by an order of nature—between the first form of the element and the ultimate form to which generation is directed: for nature proceeds in an orderly manner in its works, and does not produce anything from one extreme to another except through means essentially and by degrees ordered.

VII. To the first argument, therefore, the opposite can be said ¹⁷ in two ways. First, that Saint Thomas is not speaking there of the matter of one element in relation to all forms, but in relation to the forms of the other elements, which are introduced into it by simple generation. For it, once stripped of one elemental form, can indifferently receive several elemental forms: because, as is said here, each of them has a form immediately from prime matter. Hence he also cites ¹⁸ Aristotle, II de Gen. ¹⁹, who says that, when fire is made from earth, there is no need for a passage through the intermediate elements. He speaks, however, particularly of those forms, because from the contrariety among them it was argued that there was contrariety in substance. But he himself shows that on account of them one need not posit contrariety in substance: since neither is found among them the greatest distance, such that one could not pass from one of them except through intermediaries; nor could their esse be acquired through continuous motion. And thus, since there is no contrariety among those forms between which it seems especially to exist on account of their contrary qualities, much less will there be contrariety among the other substantial forms. — Here, however, Saint Thomas, in the passage cited, is not speaking of matter in relation to the elemental forms to be introduced into it by simple generation, but in relation to other forms which are above the elemental forms.

It can be answered secondly, in accordance with what is said in the Qu. de Spiritualibus, at the place cited ²⁰, that Saint Thomas speaks in V Physics of matter itself considered in itself and nakedly. For matter itself, stripped of one form, as such, that is, without form, insofar as its own nature and potentiality are concerned, is indifferent to receiving any form whatever, because every substantial form is by nature apt to give it esse immediately and to be united with it immediately. — But here Saint Thomas speaks of matter insofar as it is disposed by an agent and ordered toward generation. For thus, when it has been disposed by some agent toward the generation of a certain thing, and through that agent's action has been stripped of the form it had, as such, that is, stripped of it by such an agent, it is not indifferent to several forms, but is determined to that one toward which the agent had disposed it. Hence there is no contradiction.

2. To the second ²¹, it is clear from what has been said that it is one thing for a form to be, by the order of nature, immediately related to matter, and another for that same form to be united to matter immediately. Therefore Saint Thomas does not prove that the generation of simple bodies does not proceed in an orderly way because each of the elements has a form by which it is immediately united to matter, but because each of them has a form that is, by the order of nature, immediately related to matter. This, however, does not belong to every form, but only to the forms of the elements, because they hold the lowest degree among forms.

VIII. Concerning the sixth statement ²², where it is said that neither is alteration as a whole continuous, nor growth as a whole, it must be noted that from these words it does not follow that no alteration whatsoever is continuous nor any growth whatsoever; for this, since it was said only incidentally, Saint Thomas did not intend to assert, because it involves many difficulties. Rather, what follows is only that alteration as a whole—namely, that by which something is altered from not having a certain degree of a quality to having some perfect degree—is not necessarily continuous; for a mobile can be moved toward some remiss degree, and, after resting there for some time, be moved toward the perfect degree. Similarly, the whole growth by which an animal grows throughout its entire life is not continuous: since we see a man grow to a certain quantity and rest at that quantity for a long space of time, and then grow again to an even greater quantity. Of this there is no doubt. But whether partial growth and partial alteration are continuous motions does not belong to the present inquiry, but pertains to Physics VIII, which we treated there ²³.

IX. As to the second point, Saint Thomas responds to each argument ²⁴. To the first, he denies the antecedent; and to its proof, he denies the consequence: for although the sensitive soul of a brute animal and the sensitive soul of a man are of the same genus, they are not of the same species, just as neither are man and brute animal of the same species. — To the proof, he denies the assumption. For diversity of species can require a different mode of coming into being in things that are of the same genus. In the case at hand, the soul of a brute is only sensitive, and consequently neither its esse nor its operation is raised above the body: therefore it is generated and corrupted together with the body. But the sensitive soul of man is also intellective, and with respect to both esse and operation it is raised above the body: therefore it is not generated by the generation of the body.

To the second, he answers from what has been said that the sensitive soul by which the fetus was an animal does not remain, but another succeeds to it, which is at once both sensitive and intellective.

X. To the foundation of the third argument, namely that the actions of different agents are not terminated at one fact but at diverse ones, he replies that this is true of agents not subordinated; it is false, however, of subordinated agents, of which one is as the principal agent and the other as an instrument ²⁵.

It is said, however, second, that sometimes the principal action of the agent reaches to something in what is produced that the action of the instrument does not reach. And thus, in one and the same thing generated, which is man, nothing prevents the action of nature, which is as it were God's instrument, from being terminated at something of man, but not at the whole that comes about by God's action. Hence by the power of God and the power of the seed the body of man is indeed produced: but the soul the action of God produces immediately, which the power of the seed cannot produce, though it disposes toward it.

2. For the clarification of this answer, it must be considered that, although the power of the seed is said not to produce the soul but only to dispose toward it, this is nevertheless not to be understood in such a sense that the power of the seed in no way reaches the soul itself: rather the meaning is, as is had from Quodlibet de Potentia, q. III, a. 9, in the solutions to the arguments, that it does not produce the soul by causing its esse, but produces the dispositions that are necessary for the form, and by which the body is disposed so as to be a partaker of the esse of the soul; and because upon such dispositions there follows the union of the soul with the body, therefore the power of the seed is also the cause of the union of the soul with matter. — And by this many arguments brought forward by Capreolus are solved, in II Sent., d. xv ²⁶, by which it is argued that the generation of man from man cannot be saved if man produces only accidental dispositions. For it is said that the natural agent causes not only the dispositions of the body, but is also the cause of the union of the soul with the body dispositively: and thus the natural agent is said to induce the form into matter.

XI. But against this answer, when it is said that subordinate agents, such as God and a creature with respect to man, can act toward the same terminus in different ways, a doubt is raised. For in the generation of man the divine action, which is creation, cannot be terminated at the same composite which is man, at which the action of man, which is generation, is terminated: otherwise the whole man would be said to be created, just as he is said to be begotten. Nor to the same terminus, which is the form: for then the created agent would cooperate in creation, whose opposite was shown in what precedes ²⁷. Therefore they are not terminated at the same terminus in any way.

It is answered, and first it is said, that the action of God and the action of the seed, or of the man generating, terminate at the same terminus, which is man, and at the same terminus, which is the soul, but in different ways. For man is the terminus of creation insofar as his principal part, namely the intellective soul, is created in the body. He is, however, the terminus of generation insofar as the other part, namely the body, is disposed by generation with a final disposition to receive the soul; and generation is the cause, by the mode of disposing and preparing the matter, that the soul be united to it, from which union results that whole which is man; for that which unites matter with form is, in its own way, the cause of the composite that results from such a union. — The soul, however, is the terminus of creation with respect to its esse absolutely considered. It is, however, the formal terminus of generation with respect to its union with matter.

But when it is said that then a created agent would cooperate with creation, I say that cooperating with creation can be understood in two ways. In one way, because with another it works toward attaining the esse of the term of creation itself absolutely. And thus nothing cooperates with creation. — In another way, by disposing the matter in which the per se term of creation is created, and thereby uniting the term of creation to matter. And thus there is no incongruity in something's cooperating with the creation of a thing that is created in determinate matter. And thus we say that man, or the power of the seed, cooperates with the creation of the soul.

2. But another doubt arises, one also touched upon by Capreolus at the cited place ²⁸ For since it is said that the power of the seed is the cause of the dispositions of the body, but not of the soul, a question is raised about those dispositions. Either they follow the soul in the order of nature, or they precede it. Not the first, both because no agent causes accidents consequent upon some form unless it causes that form, and because the power of the seed causes nothing after it has deposited the fetus in its species. — Nor the second. Because then there would be in man another substantial form preceding the soul, on which they would be founded: which has been denied. — Therefore in no way does the power of the seed cause those dispositions unless it also causes the soul itself.

It is answered that there is a twofold genus of dispositions of matter. For some are transitory dispositions, by which, namely, matter is prepared for the reception of the soul, but which cease to be at its advent. And it is certain that such dispositions precede the soul and are founded in a substantial form preceding in matter the advent of the soul: as are the accidents of the embryo, which follow the sensitive soul existing in it. But some are permanent dispositions, which, namely, are caused in the very instant in which the soul is united to the body, and remain together with the soul in matter. Such dispositions, as has been most fully shown above ²⁹, speaking absolutely, follow the soul: for it is necessary, in the order of nature, that the form be united to matter before the accidents of the composite exist, because the composite results from the union of the form with matter; but the accidents which are caused by the natural agent in the very introduction of the soul are accidents not of the soul alone, as intellect and will, which are caused by God alone; nor of matter alone, since every substantial form, as was shown above ³⁰, is united immediately to matter; but they are accidents of the composite. Yet, if the soul is considered as giving intellectual esse, they precede the soul itself in the genus of material cause, as its dispositions, by which matter is prepared for intellectual esse.

When it is proved that the soul does not follow upon matter: to the first proof it is said that the assumption was true of the accidents consequent upon the form alone, as its properties existing in it alone; but it is not true of the accidents of the composite, of which we are speaking in our proposal, and of the instrumental agent preparing matter, through passing accidents, for the reception of the form—such as is the natural agent of which we are now speaking. For such an agent is the dispositive cause of the union of the form with matter; and consequently it is the cause of the composite and of the accidents that accompany the composite.

To the second it is said that the natural agent produces nothing after the fetus has been established in the species, by a posteriority of duration. But well indeed, in the very instant in which the fetus is established in the species, something acts that follows the union of the soul with matter by a posteriority of nature, and also precedes the form according to some consideration, as we said of accidents of this kind.

But when it is proved that they do not precede, because in man there would be another form besides the soul: the consequence is denied. For it is said that those dispositions, insofar as they precede the soul inasmuch as it gives rational esse, are founded upon the composite of matter and the intellective soul itself insofar as it gives sensitive esse. And thus there is no need to posit another form besides the intellective one in man. — From these many objections brought forward by Capreolus can be solved.

XII. To the fourth it is answered by denying the consequence. For man generates a being like himself in species insofar as the power of the seed works dispositively toward that ultimate form through which man attains his species.

For the declaration of this response, it must be noted that, because the intellective soul is of a different condition from the condition of the other forms that are in matter, therefore man is said to generate man in one way, and in another way any other animal generates an animal similar to itself in species. For because the souls of brutes depend on matter with respect to their esse, the generator in them is not only the cause of the composite, but also of the form, drawing it out from the potency of matter. But since the intellective soul does not depend on matter with respect to its esse, and is not drawn out from its potency, man generating does not cause the intellective soul absolutely, but unites it to matter, disposing matter by such a disposition as is necessary for the form. And because from such a union of the soul with matter there results the whole which is man, therefore man is said to generate man, and to produce one like himself in species.

But it must be noted here that when we say that the generating man is the cause of the union of the soul with matter, this is not to be understood as though he were the cause of the relation of union on the side of the soul, by touching that relation itself; for a relation is not per se the terminus of an action. Nor is it because he is the cause of the substantial esse in which soul and body are united. Rather, it is because he causes the terminus of the soul's relation to the body: for the sake of the positing of that terminus, namely the body, it is necessary for the soul to be united to the body according to its esse. Hence the union of matter with form, with respect to the foundation of the relation, is the intrinsic terminus of generation; but the union of form with matter on the part of the form itself and of its esse, in which the union comes about, is the extrinsic terminus of generation.

And this is what is particular in the generation of man: namely, that a man is said to generate a man for this reason alone, that through many generations and alterations he disposes the matter for the reception of the soul, and also causes dispositions that remain with it, and by this causes its union with the matter, and consequently humanity, which is the third entity. For in other generations, besides all these things, the generator also produces the very form in esse, and draws it out of the potency of the matter. But this happens because other forms are not subsistent, whereas the intellectual soul is subsistent, and is raised above matter. Therefore Saint Thomas answered well and briefly, since for it to be preserved that man generates one like himself in species, it suffices that he work dispositively toward the intellectual soul.

XIII. To the fifth argument, which is that of Apollinaris, it is answered that what is inferred is not absurd: since generation is not an act of the will but of nature, and nature is not evil.

To the sixth argument, taken from Gregory of Nyssa with the following words, the reply is made by denying the antecedent as it concerns the body insofar as it is in potency to the soul, that is, not yet having a soul. — To the proof, the consequence is denied. For then it is not yet a human body except in potency. Therefore it precedes the soul as potency precedes act; but the same thing does not precede itself.

To the seventh argument, he denies the consequence. For God's action produces both, namely the soul and the body: the body indeed by means of the power of the seed, but the soul immediately. Now the action of the seed brings to completion that for which it exists.

Note that Saint Thomas, by this response, wishes to deny this proposition: An action which does not produce the whole thing into being is imperfect. For an action is not called imperfect because it does not produce the whole thing, when it is not ordered to the production of the thing with respect to all its parts, but only to the production of one part. For every action is perfect in its own genus when through it that to which it is ordered is completed. And therefore, since the power of the seed is not ordered by nature to the production of man with respect to every part of him, but only to the disposition and organization of the body sufficient for the reception of the intellectual soul, therefore, if through it this is accomplished, it is a perfect action, even granted that it does not produce both parts of man.

2. But a doubt arises concerning what is said of the divine action. For if God produces the body by means of the power of the seed, but the soul immediately, it follows that two divine actions concur simultaneously in the production of man, namely, the creation of the soul and the production of the body. But one thing cannot be produced simply by the same agent through a twofold action of his: for to each action there corresponds its own proper and distinct terminus. Therefore man will not be one thing simply: which St. Thomas held to be an absurdity, against Plato and Origen, above ³¹.

It is said first, that certainly two extrinsic operations of God concur in the production of man: although his intrinsic operation is one alone, which is the divine substance.

It is said second, that one thing simply can be produced by two actions of the same agent, when one is ordered to the other: as when the principal agent moves an instrument, and produces something else to which the action of the instrument does not reach. For that action by which it reaches something through the instrument by way of disposition, it orders to the action by which it produces a further effect: just as what is produced through the instrument is ordered as a disposition to the principal effect. So it is in the case at hand. For the action by which God, through the mediation of the power of the seed, produces the body is ordered to the creation of the soul in the body: just as the body is ordered to the soul as its proper matter.

XIV. To the eighth argument he responds by denying the consequence. — To the proof, he denies the assumption concerning the part that exceeds the whole bodily power, as is the soul.

To the ninth argument it responds by denying both the consequence and the assumption offered in its proof. For through that manifestation of the soul's operations according to the body's development, it is shown that the disposition of the parts of the body is necessary for the soul's operation; but not that one and the same principle has both soul and body.

To the tenth, he says that indeed the body is configured through the soul of the generator: not however through the soul of the one begotten, as was shown above. Therefore it does not follow that the soul of the begotten is in the seed.

To make this answer evident, we must consider, according to the doctrine of Saint Thomas in the Power, above ³², ad 5, that although the power of the seed does not reach the intellectual soul itself by producing it, it must nevertheless dispose the matter by the power of the soul of the man generating. For it would not act toward such a disposition of the matter that a body capable of being perfected by a rational soul may come to be, unless it acted by the power of the rational soul as its instrument: since we see that no body is apt for the rational soul except the body generated from the seed of man. And because such a disposition is made by configuring and organizing the body so that through it the soul can exercise its operations, therefore it is rightly said here that the body is configured by the power of the generating soul to the soul of the one generated.

To the eleventh he responds that, as is clear from what has been said, the seed is not living from the beginning except in potency, and consequently it does not then have a soul in act. In the course of generation, however, it has a vegetative and sensitive soul by the power of the seed; but those souls, when the intellective soul succeeds, pass away ³³.

It must be noted that when it is said that the seed has the vegetative and sensitive soul by the power of the seed, the seed has two things, as is clear from what was said above ³⁴: namely, a corporeal and frothy substance; and the spirits enclosed within it. From the corporeal substance the body is generated: and this is the reason why the seed is said to be living from the beginning in passive potency and afterwards living in act. In the enclosed spirits, however, is the power of the generating soul: and by reason of this it is said that the seed has the vegetative and sensitive soul by the power of the seed, that is, by the power existing in the spirits enclosed in the seed. And thus the seed, in one respect, is matter, and in another respect is agent.

XV. A doubt arises, however, concerning what is said here, and was said above ³⁵, namely that at the advent of the rational soul the pre-existing sensitive soul—which is also vegetative—recedes. For it is asked: from what is it corrupted? Not from the power of the seed: for a natural agent does not corrupt any form except by introducing another. Nor from a supernatural agent: for what is generated naturally is also corrupted naturally. Therefore it does not cease through the advent of the rational soul.

Furthermore, it would follow that in man nothing would be truly generated. For matter is not generated, nor is form. And if the preceding form is corrupted when the intellective soul arrives, the intellective soul comes to naked matter. Therefore nothing there will be generated.

Further. If the preceding form is corrupted and there is a resolution all the way to prime matter, because once the substantial form is removed all the accidents consequent upon it are removed as well, it follows that matter would have been disposed in vain by the preceding forms. But nature does nothing in vain ³⁶. Therefore, etc.

XVI. For the clarification of this point, it must be considered that, as is clear from what was said above ³⁷, because the intellective soul gives substantial esse and makes a being simply in act, just as any other substantial form does, therefore it does not admit alongside itself another substantial form in matter; for thus it would come to a being already in act, and consequently would be an accidental form, not a substantial one. But when it comes to matter, the preceding form must necessarily be corrupted. Yet those who attack St. Thomas on this point are deceived, because they imagine that at some prior moment in duration matter is stripped of every form, and then at some later instant the soul is introduced into matter existing naked and stripped—as if the stripping of matter of every form were some disposition preceding the introduction of the intellective soul. But this is not the mind of St. Thomas. Rather we say that matter is prepared through many alterations, through many generations and corruptions, for the reception of the intellective soul; and when it has been sufficiently prepared, the intellective soul comes to matter in an instant, while that matter exists under the sensitive soul, and in that same instant it formally expels the sensitive soul together with all its dispositions, and gives to matter whatever the sensitive soul was giving; so that the same instant is the first non-being of the sensitive soul and the first being of the intellective soul. Hence the denudation of matter from every form absolutely speaking is not the total disposition for the intellective soul, for then the intellective soul could be introduced into any matter whatever; but its denudation from the sensitive soul immediately preceding in matter—a denudation, I say, made by the expulsion of that form upon the advent of the intellective soul, together with dispositions similar to those tending toward the esse of the intellective soul.

2. With this supposition, it is said to the first that the preceding sensitive soul is corrupted both by a natural agent and by a supernatural agent. For since the intellectual soul cannot exist together with it in matter, every agent acting toward the introduction of the intellectual soul into matter also acts toward the corruption of the preceding form. — But when it is objected that it is not corrupted by a natural agent, it is said that the natural agent, that is, the power existing in the seed, corrupts the sensitive soul by introducing the intellectual soul dispositively; for it produces in the instant of the introduction of the intellectual soul itself those dispositions which remain together with the soul itself, and which we have said ³⁸ precede the intellectual soul in the order of nature insofar as it gives rational esse, although they follow it absolutely. — And when it is further argued that it is not corrupted by a supernatural agent, it has already been stated that it is not corrupted by the supernatural agent alone, but the action of the power of the seed concurs as well. Hence, just as in generating a man the seed is an instrument of the divine power, so too in corrupting the forms previously introduced.

To the second, the consequence is denied. — To the proof it is said that, although neither matter nor form is generated, nevertheless a third entity, which results from matter and form, namely man, is truly generated. For although in the generation of other animals the whole is said to be generated, because even the form itself receives esse through generation: yet in the generation of man, because the soul is raised above matter, the generator is said to generate man from that alone by which he causes dispositively the union of body and soul, from which union man results; and this the generator does by disposing the matter with dispositions that pass away, and with dispositions that remain together with the soul. But the argument proceeds as if we were saying that a resolution is made all the way to prime matter, and that no effect of generation remains in the begotten man. This, however, we do not say: but rather that all the accidents which existed before the instant of the soul's introduction cease to be, yet in that same instant similar accidents are introduced by the power of the generator, and those remain together with the union of soul and body, which is also an effect of the generator.

To the third, the consequence is denied. For it was necessary that the vegetative and sensitive soul be introduced into matter beforehand, even though they are corrupted, because matter cannot pass from the lowest form to the highest except through intermediate forms, as was shown above ³⁹. And therefore nature introduces those forms into matter beforehand as dispositions in becoming of the intellectual soul itself, but not as dispositions in its state of being. Hence they are not introduced in vain: except when the corruption of the embryo happens before the intellectual soul is formed. For since that is in vain which does not attain the end to which it is ordered ⁴⁰, if through dispositions of this kind one arrives at the introduction of the soul, which is their end, then although, on account of the incompatibility of two substantial forms in the same matter, they are corrupted at the very introduction of the soul, they are not said to have been introduced in vain. Hence Saint Thomas said above that the intermediate forms do not possess a complete species, but are on the way to the species: and therefore they are not generated so as to remain, but so that through them one may arrive at the ultimate thing generated.

XVII. To the twelfth he responds by denying the first consequence. To the proof it is said that something can be for the sake of another in two ways. In one way, because it is for the sake of something that follows upon its being: for instance, for the sake of its operation or its preservation. And this is posterior to that for the sake of which it is. And thus garments are for the sake of man. — In another way, because it is for the sake of its esse. And such a thing is prior to it in time, but posterior in nature. And in this way the body is for the sake of the soul, as matter is for the sake of form. — It would be otherwise, however, if we were to hold that from body and soul there is not made one thing in esse: as some say that the soul is not the form of the body.

Doubt is raised concerning this last statement. For even if it were granted that no unity comes about from soul and body, it would not on that account be necessary to say that the soul exists for the sake of the body, as is said here. For the body could be disposed to the esse of the soul itself not in the manner of matter, but in the manner of a vessel into which the soul, newly created, would be received. And thus the body would be for the sake of the soul, and not conversely the soul for the sake of the body.

It is answered that St. Thomas is speaking of the opinion of those who held that souls were produced before bodies, and were complete natures in themselves, but that after the production of the bodies they were united to them; against whom it was disputed above ⁴¹ For on this view it follows that souls are united to bodies on account of the nobility and perfection of the bodies themselves, and not because they need them for their esse from the beginning of creation. And consequently the soul will be for the sake of the body, not the body for the sake of the soul.