Summa Th. I-II EN Qu.81 a.3
1623
Objection: 1. It would seem that the sin of the first parent is not transmitted, by the way of origin, to all men. Because death is a punishment consequent upon original sin. But not all those, who are born of the seed of Adam, will die: since those who will be still living at the coming of our Lord, will never die, as, seemingly, may be gathered from 1 Thess. 4:14: "We who are alive . . . unto the coming of the Lord, shall not prevent them who have slept." Therefore they do not contract original sin.
2. Further, no one gives another what he has not himself. Now a man who has been baptized has not original sin. Therefore he does not transmit it to his children.
3. Further, the gift of Christ is greater than the sin of Adam, as the Apostle declares (Rm 5,15, seqq). But the gift of Christ is not transmitted to all men: neither, therefore, is the sin of Adam.
On the contrary The Apostle says (Rm 5,12): "Death passed upon all men in whom all have sinned."
I answer that According to the Catholic Faith we must firmly believe that, Christ alone excepted, all men descended from Adam contract original sin from him; else all would not need redemption [*Cf. Translator's note inserted before III 27,0] which is through Christ; and this is erroneous. The reason for this may be gathered from what has been stated (Article [1]), viz. that original sin, in virtue of the sin of our first parent, is transmitted to his posterity, just as, from the soul's will, actual sin is transmitted to the members of the body, through their being moved by the will. Now it is evident that actual sin can be transmitted to all such members as have an inborn aptitude to be moved by the will. Therefore original sin is transmitted to all those who are moved by Adam by the movement of generation.
Reply to Objection: 1. It is held with greater probability and more commonly that all those that are alive at the coming of our Lord, will die, and rise again shortly, as we shall state more fully in the TP (XP, Question [78], Article [1], Objection [1]). If, however, it be true, as others hold, that they will never die, (an opinion which Jerome mentions among others in a letter to Minerius, on the Resurrection of the Body---Ep. cxix), then we must say in reply to the objection, that although they are not to die, the debt of death is none the less in them, and that the punishment of death will be remitted by God, since He can also forgive the punishment due for actual sins.
2. Original sin is taken away by Baptism as to the guilt, in so far as the soul recovers grace as regards the mind. Nevertheless original sin remains in its effect as regards the "fomes," which is the disorder of the lower parts of the soul and of the body itself, in respect of which, and not of the mind, man exercises his power of generation. Consequently those who are baptized transmit original sin: since they do not beget as being renewed in Baptism, but as still retaining something of the oldness of the first sin.
3. Just as Adam's sin is transmitted to all who are born of Adam corporally, so is the grace of Christ transmitted to all that are begotten of Him spiritually, by faith and Baptism: and this, not only unto the removal of sin of their first parent, but also unto the removal of actual sins, and the obtaining of glory.
1624
Objection: 1. It would seem that original sin would be contracted by a person formed miraculously from human flesh. For a gloss on Gn 4,1 says that "Adam's entire posterity was corrupted in his loins, because they were not severed from him in the place of life, before he sinned, but in the place of exile after he had sinned." But if a man were to be formed in the aforesaid manner, his flesh would be severed in the place of exile. Therefore it would contract original sin.
2. Further, original sin is caused in us by the soul being infected through the flesh. But man's flesh is entirely corrupted. Therefore a man's soul would contract the infection of original sin, from whatever part of the flesh it was formed.
3. Further, original sin comes upon all from our first parent, in so far as we were all in him when he sinned. But those who might be formed out of human flesh, would have been in Adam. Therefore they would contract original sin.
On the contrary They would not have been in Adam "according to seminal virtue," which alone is the cause of the transmission of original sin, as Augustine states (Gn ad lit. x, 18, seqq.).
I answer that As stated above (Articles [1],3), original sin is transmitted from the first parent to his posterity, inasmuch as they are moved by him through generation, even as the members are moved by the soul to actual sin. Now there is no movement to generation except by the active power of generation: so that those alone contract original sin, who are descended from Adam through the active power of generation originally derived from Adam, i.e. who are descended from him through seminal power; for the seminal power is nothing else than the active power of generation. But if anyone were to be formed by God out of human flesh, it is evident that the active power would not be derived from Adam. Consequently he would not contract original sin: even as a hand would have no part in a human sin, if it were moved, not by the man's will, but by some external power.
Reply to Objection: 1. Adam was not in the place of exile until after his sin. Consequently it is not on account of the place of exile, but on account of the sin, that original sin is transmitted to those to whom his active generation extends.
2. The flesh does not corrupt the soul, except in so far as it is the active principle in generation, as we have stated.
3. If a man were to be formed from human flesh, he would have been in Adam, "by way of bodily substance" [*The expression is St. Augustine's (Gn ad lit. x). Cf. Summa Theologica III 31,6, Reply to Objection [1]], but not according to seminal virtue, as stated above. Therefore he would not contract original sin. Aquin.: SMT FS Question [81] Article [5] Thes. Para. 1/1 Whether if Eve, and not Adam, had sinned, their children would have contracted original sin? Aquin.: SMT FS Question [81] Article [5] Obj. 1 Para. 1/1 OBJ 1: It would seem that if Eve, and not Adam, had sinned, their children would have contracted original sin. Because we contract original sin from our parents, in so far as we were once in them, according to the word of the Apostle (Rm 5,12): "In whom all have sinned." Now a man pre-exist in his mother as well as in his father. Therefore a man would have contracted original sin from his mother's sin as well as from his father's.
#1625
Objection: 1.
2. Further, if Eve, and not Adam, had sinned, their children would have been born liable to suffering and death, since it is "the mother" that "provides the matter in generation" as the Philosopher states (De Gener. Animal. ii, 1,4), when death and liability to suffering are the necessary results of matter. Now liability to suffering and the necessity of dying are punishments of original sin. Therefore if Eve, and not Adam, had sinned, their children would contract original sin.
3. Further, Damascene says (De Fide Orth. iii, 3) that "the Holy Ghost came upon the Virgin," (of whom Christ was to be born without original sin) "purifying her." But this purification would not have been necessary, if the infection of original sin were not contracted from the mother. Therefore the infection of original sin is contracted from the mother: so that if Eve had sinned, her children would have contracted original sin, even if Adam had not sinned.
On the contrary The Apostle says (Rm 5,12): "By one man sin entered into this world." Now if the woman would have transmitted original sin to her children, he should have said that it entered by two, since both of them sinned, or rather that it entered by a woman, since she sinned first. Therefore original sin is transmitted to the children, not by the mother, but by the father.
I answer that The solution of this question is made clear by what has been said. For it has been stated (Article [1]) that original sin is transmitted by the first parent in so far as he is the mover in the begetting of his children: wherefore it has been said (Article [4]) that if anyone were begotten materially only, of human flesh, they would not contract original sin. Now it is evident that in the opinion of philosophers, the active principle of generation is from the father, while the mother provides the matter. Therefore original sin, is contracted, not from the mother, but from the father: so that, accordingly, if Eve, and not Adam, had sinned, their children would not contract original sin: whereas, if Adam, and not Eve, had sinned, they would contract it.
Reply to Objection: 1. The child pre-exists in its father as in its active principle, and in its mother, as in its material and passive principle. Consequently the comparison fails.
2. Some hold that if Eve, and not Adam, had sinned, their children would be immune from the sin, but would have been subject to the necessity of dying and to other forms of suffering that are a necessary result of the matter which is provided by the mother, not as punishments, but as actual defects. This, however, seems unreasonable. Because, as stated in the I 97,1 I 97,2, ad 4, immortality and impassibility, in the original state, were a result, not of the condition of matter, but of original justice, whereby the body was subjected to the soul, so long as the soul remained subject to God. Now privation of original justice is original sin. If, therefore, supposing Adam had not sinned, original sin would not have been transmitted to posterity on account of Eve's sin; it is evident that the children would not have been deprived of original justice: and consequently they would not have been liable to suffer and subject to the necessity of dying.
3. This prevenient purification in the Blessed Virgin was not needed to hinder the transmission of original sin, but because it behooved the Mother of God "to shine with the greatest purity" [*Cf. Anselm, De Concep. Virg. xviii.]. For nothing is worthy to receive God unless it be pure, according to Ps 92,5: "Holiness becometh Thy House, O Lord."
1640
We must now consider original sin as to its essence, and under this head there are four points of inquiry:
(1) Whether original sin is a habit?
(2) Whether there is but one original sin in each man?
(3) Whether original sin is concupiscence?
(4) Whether original sin is equally in all?
1641
Objection: 1. It would seem that original sin is not a habit. For original sin is the absence of original justice, as Anselm states (De Concep. Virg. ii, iii, xxvi), so that original sin is a privation. But privation is opposed to habit. Therefore original sin is not a habit.
2. Further, actual sin has the nature of fault more than original sin, in so far as it is more voluntary. Now the habit of actual sin has not the nature of a fault, else it would follow that a man while asleep, would be guilty of sin. Therefore no original habit has the nature of a fault.
3. Further, in wickedness act always precedes habit, because evil habits are not infused, but acquired. Now original sin is not preceded by an act. Therefore original sin is not a habit.
On the contrary Augustine says in his book on the Baptism of infants (De Pecc. Merit. et Remiss. i, 39) that on account of original sin little children have the aptitude of concupiscence though they have not the act. Now aptitude denotes some kind of habit. Therefore original sin is a habit.
I answer that As stated above (Question [49], Article [4]; Question [50], Article [1]), habit is twofold. The first is a habit whereby power is inclined to an act: thus science and virtue are called habits. In this way original sin is not a habit. The second kind of habit is the disposition of a complex nature, whereby that nature is well or ill disposed to something, chiefly when such a disposition has become like a second nature, as in the case of sickness or health. In this sense original sin is a habit. For it is an inordinate disposition, arising from the destruction of the harmony which was essential to original justice, even as bodily sickness is an inordinate disposition of the body, by reason of the destruction of that equilibrium which is essential to health. Hence it is that original sin is called the "languor of nature" [*Cf. Augustine, In Ps. 118, serm. iii].
Reply to Objection: 1. As bodily sickness is partly a privation, in so far as it denotes the destruction of the equilibrium of health, and partly something positive, viz. the very humors that are inordinately disposed, so too original sin denotes the privation of original justice, and besides this, the inordinate disposition of the parts of the soul. Consequently it is not a pure privation, but a corrupt habit.
2. Actual sin is an inordinateness of an act: whereas original sin, being the sin of nature, is an inordinate disposition of nature, and has the character of fault through being transmitted from our first parent, as stated above (Question [81], Article [1]). Now this inordinate disposition of nature is a kind of habit, whereas the inordinate disposition of an act is not: and for this reason original sin can be a habit, whereas actual sin cannot.
3. This objection considers the habit which inclines a power to an act: but original sin is not this kind of habit. Nevertheless a certain inclination to an inordinate act does follow from original sin, not directly, but indirectly, viz. by the removal of the obstacle, i.e. original justice, which hindered inordinate movements: just as an inclination to inordinate bodily movements results indirectly from bodily sickness. Nor is it necessary to says that original sin is a habit "infused," or a habit "acquired" (except by the act of our first parent, but not by our own act): but it is a habit "inborn" due to our corrupt origin.
1642
Objection: 1. It would seem that there are many original sins in one man. For it is written (Ps 1,7): "Behold I was conceived in iniquities, and in sins did my mother conceive me." But the sin in which a man is conceived is original sin. Therefore there are several original sins in man.
2. Further, one and the same habit does not incline its subject to contraries: since the inclination of habit is like that of nature which tends to one thing. Now original sin, even in one man, inclines to various and contrary sins. Therefore original sin is not one habit; but several.
3. Further, original sin infects every part of the soul. Now the different parts of the soul are different subjects of sin, as shown above (Question [74]). Since then one sin cannot be in different subjects, it seems that original sin is not one but several.
On the contrary It is written (Jn 1,29): "Behold the Lamb of God, behold Him Who taketh away the sin of the world": and the reason for the employment of the singular is that the "sin of the world" is original sin, as a gloss expounds this passage.
I answer that In one man there is one original sin. Two reasons may be assigned for this. The first is on the part of the cause of original sin. For it has been stated (Question [81], Article [2]), that the first sin alone of our first parent was transmitted to his posterity. Wherefore in one man original sin is one in number; and in all men, it is one in proportion, i.e. in relation to its first principle. The second reason may be taken from the very essence of original sin. Because in every inordinate disposition, unity of species depends on the cause, while the unity of number is derived from the subject. For example, take bodily sickness: various species of sickness proceed from different causes, e.g. from excessive heat or cold, or from a lesion in the lung or liver; while one specific sickness in one man will be one in number. Now the cause of this corrupt disposition that is called original sin, is one only, viz. the privation of original justice, removing the subjection of man's mind to God. Consequently original sin is specifically one, and, in one man, can be only one in number; while, in different men, it is one in species and in proportion, but is numerically many.
Reply to Objection: 1. The employment of the plural---"in sins"---may be explained by the custom of the Divine Scriptures in the frequent use of the plural for the singular, e.g. "They are dead that sought the life of the child"; or by the fact that all actual sins virtually pre-exist in original sin, as in a principle so that it is virtually many; or by the fact of there being many deformities in the sin of our first parent, viz. pride, disobedience, gluttony, and so forth; or by several parts of the soul being infected by original sin.
2. Of itself and directly, i.e. by its own form, one habit cannot incline its subject to contraries. But there is no reason why it should not do so, indirectly and accidentally, i.e. by the removal of an obstacle: thus, when the harmony of a mixed body is destroyed, the elements have contrary local tendencies. In like manner, when the harmony of original justice is destroyed, the various powers of the soul have various opposite tendencies.
3. Original sin infects the different parts of the soul, in so far as they are the parts of one whole; even as original justice held all the soul's parts together in one. Consequently there is but one original sin: just as there is but one fever in one man, although the various parts of the body are affected.
1643
Objection: 1. It would seem that original sin is not concupiscence. For every sin is contrary to nature, according to Damascene (De Fide Orth. ii, 4,30). But concupiscence is in accordance with nature, since it is the proper act of the concupiscible faculty which is a natural power. Therefore concupiscence is not original sin.
2. Further, through original sin "the passions of sins" are in us, according to the Apostle (Rm 7,5). Now there are several other passions besides concupiscence, as stated above (Question [23], Article [4]). Therefore original sin is not concupiscence any more than another passion.
3. Further, by original sin, all the parts of the soul are disordered, as stated above (Article [2], Objection [3]). But the intellect is the highest of the soul's parts, as the Philosopher states (Ethic. x, 7). Therefore original sin is ignorance rather than concupiscence.
On the contrary Augustine says (Retract. i, 15): "Concupiscence is the guilt of original sin."
I answer that Everything takes its species from its form: and it has been stated (Article [2]) that the species of original sin is taken from its cause. Consequently the formal element of original sin must be considered in respect of the cause of original sin. But contraries have contrary causes. Therefore the cause of original sin must be considered with respect to the cause of original justice, which is opposed to it. Now the whole order of original justice consists in man's will being subject to God: which subjection, first and chiefly, was in the will, whose function it is to move all the other parts to the end, as stated above (Question [9], Article [1]), so that the will being turned away from God, all the other powers of the soul become inordinate. Accordingly the privation of original justice, whereby the will was made subject to God, is the formal element in original sin; while every other disorder of the soul's powers, is a kind of material element in respect of original sin. Now the inordinateness of the other powers of the soul consists chiefly in their turning inordinately to mutable good; which inordinateness may be called by the general name of concupiscence. Hence original sin is concupiscence, materially, but privation of original justice, formally.
Reply to Objection: 1. Since, in man, the concupiscible power is naturally governed by reason, the act of concupiscence is so far natural to man, as it is in accord with the order of reason; while, in so far as it trespasses beyond the bounds of reason, it is, for a man, contrary to reason. Such is the concupiscence of original sin.
2. As stated above (Question [25], Article [1]), all the irascible passions are reducible to concupiscible passions, as holding the principle place: and of these, concupiscence is the most impetuous in moving, and is felt most, as stated above (Question [25], Article [2], ad 1). Therefore original sin is ascribed to concupiscence, as being the chief passion, and as including all the others, in a fashion.
3. As, in good things, the intellect and reason stand first, so conversely in evil things, the lower part of the soul is found to take precedence, for it clouds and draws the reason, as stated above (Question [77], Articles [1],2; Question [80], Article [2]). Hence original sin is called concupiscence rather than ignorance, although ignorance is comprised among the material defects of original sin.
1644
Objection: 1. It would seem that original sin is not equally in all. Because original sin is inordinate concupiscence, as stated above (Article [3]). Now all are not equally prone to acts of concupiscence. Therefore original sin is not equally in all.
2. Further, original sin is an inordinate disposition of the soul, just as sickness is an inordinate disposition of the body. But sickness is subject to degrees. Therefore original sin is subject to degrees.
3. Further, Augustine says (De Nup. et Concep. i, 23) that "lust transmits original sin to the child." But the act of generation may be more lustful in one than in another. Therefore original sin may be greater in one than in another.
On the contrary Original sin is the sin of nature, as stated above (Question [81], Article [1]). But nature is equally in all. Therefore original sin is too.
I answer that There are two things in original sin: one is the privation of original justice; the other is the relation of this privation to the sin of our first parent, from whom it is transmitted to man through his corrupt origin. As to the first, original sin has no degrees, since the gift of original justice is taken away entirely; and privations that remove something entirely, such as death and darkness, cannot be more or less, as stated above (Question [73], Article [2]). In like manner, neither is this possible, as to the second: since all are related equally to the first principle of our corrupt origin, from which principle original sin takes the nature of guilt; for relations cannot be more or less. Consequently it is evident that original sin cannot be more in one than in another.
Reply to Objection: 1. Through the bond of original justice being broken, which held together all the powers of the soul in a certain order, each power of the soul tends to its own proper movement, and the more impetuously, as it is stronger. Now it happens that some of the soul's powers are stronger in one man than in another, on account of the different bodily temperaments. Consequently if one man is more prone than another to acts of concupiscence, this is not due to original sin, because the bond of original justice is equally broken in all, and the lower parts of the soul are, in all, left to themselves equally; but it is due to the various dispositions of the powers, as stated.
2. Sickness of the body, even sickness of the same species, has not an equal cause in all; for instance if a fever be caused by corruption of the bile, the corruption may be greater or less, and nearer to, or further from a vital principle. But the cause of original sin is equal to all, so that there is not comparison.
3. It is not the actual lust that transmits original sin: for, supposing God were to grant to a man to feel no inordinate lust in the act of generation, he would still transmit original sin; we must understand this to be habitual lust, whereby the sensitive appetite is not kept subject to reason by the bonds of original justice. This lust is equally in all.
1660
We must now consider the subject of original sin, under which head there are four points of inquiry:
(1) Whether the subject of original sin is the flesh rather than the soul?
(2) If it be the soul, whether this be through its essence, or through its powers?
(3) Whether the will prior to the other powers is the subject of original sin?
(4) Whether certain powers of the soul are specially infected, viz. the generative power, the concupiscible part, and the sense of touch?
1661
Objection: 1. It would seem that original sin is more in the flesh than in the soul. Because the rebellion of the flesh against the mind arises from the corruption of original sin. Now the root of this rebellion is seated in the flesh: for the Apostle says (Rm 7,23): "I see another law in my members fighting against the law of my mind." Therefore original sin is seated chiefly in the flesh.
2. Further, a thing is more in its cause than in its effect: thus heat is in the heating fire more than in the hot water. Now the soul is infected with the corruption of original sin by the carnal semen. Therefore original sin is in the flesh rather than in the soul.
3. Further, we contract original sin from our first parent, in so far as we were in him by reason of seminal virtue. Now our souls were not in him thus, but only our flesh. Therefore original sin is not in the soul, but in the flesh.
4. Further, the rational soul created by God is infused into the body. If therefore the soul were infected with original sin, it would follow that it is corrupted in its creation or infusion: and thus God would be the cause of sin, since He is the author of the soul's creation and fusion.
5. Further, no wise man pours a precious liquid into a vessel, knowing that the vessel will corrupt the liquid. But the rational soul is more precious than any liquid. If therefore the soul, by being united with the body, could be corrupted with the infection of original sin, God, Who is wisdom itself, would never infuse the soul into such a body. And yet He does; wherefore it is not corrupted by the flesh. Therefore original sin is not in the soul but in the flesh.
On the contrary The same is the subject of a virtue and of the vice or sin contrary to that virtue. But the flesh cannot be the subject of virtue: for the Apostle says (Rm 7,18): "I know that there dwelleth not in me, that is to say, in my flesh, that which is good." Therefore the flesh cannot be the subject of original sin, but only the soul.
I answer that One thing can be in another in two ways. First, as in its cause, either principal, or instrumental; secondly, as in its subject. Accordingly the original sin of all men was in Adam indeed, as in its principal cause, according to the words of the Apostle (Rm 5,12): "In whom all have sinned": whereas it is in the bodily semen, as in its instrumental cause, since it is by the active power of the semen that original sin together with human nature is transmitted to the child. But original sin can nowise be in the flesh as its subject, but only in the soul.The reason for this is that, as stated above (Question [81], Article [1]), original sin is transmitted from the will of our first parent to this posterity by a certain movement of generation, in the same way as actual sin is transmitted from any man's will to his other parts. Now in this transmission it is to be observed, that whatever accrues from the motion of the will consenting to sin, to any part of man that can in any way share in that guilt, either as its subject or as its instrument, has the character of sin. Thus from the will consenting to gluttony, concupiscence of food accrues to the concupiscible faculty, and partaking of food accrues to the hand and the mouth, which, in so far as they are moved by the will to sin, are the instruments of sin. But that further action is evoked in the nutritive power and the internal members, which have no natural aptitude for being moved by the will, does not bear the character of guilt.Accordingly, since the soul can be the subject of guilt, while the flesh, of itself, cannot be the subject of guilt; whatever accrues to the soul from the corruption of the first sin, has the character of guilt, while whatever accrues to the flesh, has the character, not of guilt but of punishment: so that, therefore, the soul is the subject of original sin, and not the flesh.
Reply to Objection: 1. As Augustine says (Retract. i, 27) [*Cf. Questions. lxxxiii, qu. 66], the Apostle is speaking, in that passage, of man already redeemed, who is delivered from guilt, but is still liable to punishment, by reason of which sin is stated to dwell "in the flesh." Consequently it follows that the flesh is the subject, not of guilt, but of punishment.
2. Original sin is caused by the semen as instrumental cause. Now there is no need for anything to be more in the instrumental cause than in the effect; but only in the principal cause: and, in this way, original sin was in Adam more fully, since in him it had the nature of actual sin.
3. The soul of any individual man was in Adam, in respect of his seminal power, not indeed as in its effective principle, but as in a dispositive principle: because the bodily semen, which is transmitted from Adam, does not of its own power produce the rational soul, but disposes the matter for it.
4. The corruption of original sin is nowise caused by God, but by the sin alone of our first parent through carnal generation. And so, since creation implies a relation in the soul to God alone, it cannot be said that the soul is tainted through being created. On the other hand, infusion implies relation both to God infusing and to the flesh into which the soul is infused. And so, with regard to God infusing, it cannot be said that the soul is stained through being infused; but only with regard to the body into which it is infused.
5. The common good takes precedence of private good. Wherefore God, according to His wisdom, does not overlook the general order of things (which is that such a soul be infused into such a body), lest this soul contract a singular corruption: all the more that the nature of the soul demands that it should not exist prior to its infusion into the body, as stated in the I 90,4; I 118,3. And it is better for the soul to be thus, according to its nature, than not to be at all, especially since it can avoid damnation, by means of grace.
1662
Objection: 1. It would seem that original sin is not in the essence of the soul rather than in the powers. For the soul is naturally apt to be the subject of sin, in respect of those parts which can be moved by the will. Now the soul is moved by the will, not as to its essence but only as to the powers. Therefore original sin is in the soul, not according to its essence, but only according to the powers.
2. Further, original sin is opposed to original justice. Now original justice was in a power of the soul, because power is the subject of virtue. Therefore original sin also is in a power of the soul, rather than in its essence.
3. Further, just as original sin is derived from the soul as from the flesh, so is it derived by the powers from the essence. But original sin is more in the soul than in the flesh. Therefore it is more in the powers than in the essence of the soul.
4. Further, original sin is said to be concupiscence, as stated (Question [82], Article [3]). But concupiscence is in the powers of the soul. Therefore original sin is also.
On the contrary Original sin is called the sin of nature, as stated above (Question [81], Article [1]). Now the soul is the form and nature of the body, in respect of its essence and not in respect of its powers, as stated in the I 76,6. Therefore the soul is the subject of original sin chiefly in respect of its essence.
I answer that The subject of a sin is chiefly that part of the soul to which the motive cause of that sin primarily pertains: thus if the motive cause of a sin is sensual pleasure, which regards the concupiscible power through being its proper object, it follows that the concupiscible power is the proper subject of that sin. Now it is evident that original sin is caused through our origin. Consequently that part of the soul which is first reached by man's origin, is the primary subject of original sin. Now the origin reaches the soul as the term of generation, according as it is the form of the body: and this belongs to the soul in respect of its essence, as was proved in the I 76,6. Therefore the soul, in respect of its essence, is the primary subject of original sin.
Reply to Objection: 1. As the motion of the will of an individual reaches to the soul's powers and not to its essence, so the motion of the will of the first generator, through the channel of generation, reaches first of all to the essence of the soul, as stated.
2. Even original justice pertained radically to the essence of the soul, because it was God's gift to human nature, to which the essence of the soul is related before the powers. For the powers seem to regard the person, in as much as they are the principles of personal acts. Hence they are the proper subjects of actual sins, which are the sins of the person.
3. The body is related to the soul as matter to form, which though it comes second in order of generation, nevertheless comes first in the order of perfection and nature. But the essence of the soul is related to the powers, as a subject to its proper accidents, which follow their subject both in the order of generation and in that of perfection. Consequently the comparison fails.
4. Concupiscence, in relation to original sin, holds the position of matter and effect, as stated above (Question [82], Article [3]).
Summa Th. I-II EN Qu.81 a.3