Reply Obj. 1:  We do not sin except by the will as first mover; but we sin by the other powers as moved by the will.

Reply Obj. 2:  Good and evil pertain to the will as its proper objects; but the other powers have certain determinate goods and evils, by reason of which they can be the subject of virtue, vice, and sin, in so far as they partake of will and reason.

Reply Obj. 3:  The members of the body are not principles but merely organs of action:  wherefore they are compared to the soul which moves them, as a slave who is moved but moves no other.  On the other hand, the internal appetitive powers are compared to reason as free agents, because they both act and are acted upon, as is made clear in Polit.i, 3.  Moreover, the acts of the external members are actions that pass into external matter, as may be seen in the blow that is inflicted in the sin of murder.  Consequently there is no comparison. ________________________

THIRD ARTICLE [I-II, Q. 74, Art. 3]

Whether There Can Be Sin in the Sensuality?

Objection 1:  It would seem that there cannot be sin in the sensuality.  For sin is proper to man who is praised or blamed for his actions.  Now sensuality is common to us and irrational animals.  Therefore sin cannot be in the sensuality.

Obj. 2:  Further, “no man sins in what he cannot avoid,” as Augustine states (De Lib.  Arb. iii, 18).  But man cannot prevent the movement of the sensuality from being inordinate, since “the sensuality ever remains corrupt, so long as we abide in this mortal life; wherefore it is signified by the serpent,” as Augustine declares (De Trin. xii, 12, 13).  Therefore the inordinate movement of the sensuality is not a sin.

Obj. 3:  Further, that which man himself does not do is not imputed to him as a sin.  Now “that alone do we seem to do ourselves, which we do with the deliberation of reason,” as the Philosopher says (Ethic. ix, 8).  Therefore the movement of the sensuality, which is without the deliberation of reason, is not imputed to a man as a sin.

On the contrary, It is written (Rom. 7:19):  “The good which I will I do not; but the evil which I will not, that I do”:  which words Augustine explains (Contra Julian. iii, 26; De Verb.  Apost. xii, 2, 3), as referring to the evil of concupiscence, which is clearly a movement of the sensuality.  Therefore there can be sin in the sensuality.

I answer that, As stated above (AA. 2, 3), sin may be found in any power whose act can be voluntary and inordinate, wherein consists the nature of sin.  Now it is evident that the act of the sensuality, or sensitive appetite, is naturally inclined to be moved by the will.  Wherefore it follows that sin can be in the sensuality.

Reply Obj. 1:  Although some of the powers of the sensitive part are common to us and irrational animals, nevertheless, in us, they have a certain excellence through being united to the reason; thus we surpass other animals in the sensitive part for as much as we have the powers of cogitation and reminiscence, as stated in the First Part (Q. 78, A. 4).  In the same way our sensitive appetite surpasses that of other animals by reason of a certain excellence consisting in its natural aptitude to obey the reason; and in this respect it can be the principle of a voluntary action, and, consequently, the subject of sin.