Accordingly if we take passion as preceding the sinful act, it must needs diminish the sin:  because the act is a sin in so far as it is voluntary, and under our control.  Now a thing is said to be under our control, through the reason and will:  and therefore the more the reason and will do anything of their own accord, and not through the impulse of a passion, the more is it voluntary and under our control.  In this respect passion diminishes sin, in so far as it diminishes its voluntariness.

On the other hand, a consequent passion does not diminish a sin, but increases it; or rather it is a sign of its gravity, in so far, to wit, as it shows the intensity of the will towards the sinful act; and so it is true that the greater the pleasure or the concupiscence with which anyone sins, the greater the sin.

Reply Obj. 1:  Passion is the cause of sin on the part of that to which the sinner turns.  But the gravity of a sin is measured on the part of that from which he turns, which results accidentally from his turning to something else—­accidentally, i.e. beside his intention.  Now an effect is increased by the increase, not of its accidental cause, but of its direct cause.

Reply Obj. 2:  A good passion consequent to the judgment of reason increases merit; but if it precede, so that a man is moved to do well, rather by his passion than by the judgment of his reason, such a passion diminishes the goodness and praiseworthiness of his action.

Reply Obj. 3:  Although the movement of the will incited by the passion is more intense, yet it is not so much the will’s own movement, as if it were moved to sin by the reason alone. ________________________

SEVENTH ARTICLE [I-II, Q. 77, Art. 7]

Whether Passion Excuses from Sin Altogether?

Objection 1:  It would seem that passion excuses from sin altogether.  For whatever causes an act to be involuntary, excuses from sin altogether.  But concupiscence of the flesh, which is a passion, makes an act to be involuntary, according to Gal. 5:17:  “The flesh lusteth against the spirit . . . so that you do not the things that you would.”  Therefore passion excuses from sin altogether.

Obj. 2:  Further, passion causes a certain ignorance of a particular matter, as stated above (A. 2; Q. 76, A. 3).  But ignorance of a particular matter excuses from sin altogether, as stated above (Q. 6, A. 8).  Therefore passion excuses from sin altogether.

Obj. 3:  Further, disease of the soul is graver than disease of the body.  But bodily disease excuses from sin altogether, as in the case of mad people.  Much more, therefore, does passion, which is a disease of the soul.

On the contrary, The Apostle (Rom. 7:5) speaks of the passions as “passions of sins,” for no other reason than that they cause sin:  which would not be the case if they excused from sin altogether.  Therefore passion does not excuse from sin altogether.