2. Acts are specified by their objects. The better therefore the object, the more virtuous will be the act according to its species. But the end is better than the means thereto; and in the category of means the better is that which comes nearer to the end. Therefore among human acts that is the best, which tends straight to God, the last end; and after that, an act is better in its species according as its object is nearer to God.
3. Good is in human acts according as they are regulated by reason. But some acts come nearer to reason than others: acts which are acts of reason itself have more of the good of reason in them than the acts of the lower powers commanded by reason.*
4. The commandments of the law are best fulfilled by love (Chap. CXXVIII). But one man may do his duty out of greater love than another.
6. The better act is the act of the better virtue. But one virtue is better than another: thus munificence is better than liberality, and high-souled conduct in a high position (magnanimitas) than decency in a lowly state (moderantia, i.e., metriotês).
Hence it is said: He who joineth his virgin in marriage doth well: but he who joineth her not doth better (1 Cor. vii, 38).
By the same reasons it appears that not all sins are equal: for one sin goes wider of the last end than another sin, is a greater perversion of the order of reason, and does greater harm to one's neighbour. Hence it is said: Thou hast done more wicked things than they in all thy ways (Ezech. xvi, 47).
But there may seem to be some reason in the position that all virtuous acts are equal, if we consider that every virtuous act is directed to a final good: hence, if there is the same final good for all virtuous acts, they must all be equally good. -- It is to be replied that, though there is one final end of goodness, nevertheless there is a difference of degree in the good things that are referred to that end, some of them being better than others and nigher to the last end. Hence there will be degrees of goodness in the will and its acts according to the diversity of good objects to which the will and its acts are terminated, though the ultimate end be the same.*
Or again it may be argued that all sins are equal, because sin in human acts comes solely of overpassing the rule of reason: but he overpasses the rule of reason who swerves from it in a small matter, equally with him who swerves from it in a great one; just as, if a line be drawn, not to be overstepped, it comes to the same thing in court whether the trespasser has overstepped it little or much; or as a boxer is cast, once he has gone outside the limits of the ring, little or much: so then, once a man has overstepped the bounds of reason, the amount of his transgression makes no difference. On careful consideration, however, it appears that in all cases where perfection and goodness consists in a certain conformity to measure, the evil will be the greater, the greater the departure from that due conformity. Thus health consists in a due blending of humours, and beauty in a due proportion of features and limbs, and truth in a conformity of thought or speech to fact. The greater the unevenness of humours, the greater the sickness: the greater the incongruity of features or limbs, the greater the ugliness; and the greater the departure from truth, the greater the falsehood: thus the reckoning is not so false that brings in 5 for 3 as that which brings in 100 for 3. But the good of virtue consists in a certain conformity to measure: for virtue is a mean, according to due limitation under the circumstances, between contrary vices. Wickedness then is greater, the further it is out of this harmony. Nor is transgressing the limits of virtue like transgressing bounds fixed by a court. For virtue being of itself good, the transgression of it is of itself evil; and therefore the greater the departure from virtue, the greater the evil. But the transgression of a limit fixed by a court is not of itself evil, but only accidentally so, inasmuch as it is forbidden. But in these accidental connexions, though the being of one thing at all follows upon another's being at all, it does not follow that the being of the one thing in a higher degree follows upon the other's coming to be in a higher degree. Thus if a white body is musical, it does not follow that the whiter the body, the more musical: but it does follow that if whiteness is distinctive of vision, a stronger whiteness wilt be more distinctive.*
A noteworthy difference between sins is that between mortal and venial sin. A mortal sin is one that deprives the soul of spiritual life. The essence of spiritual life consists in two things, according to the likeness of natural life. Just as the body lives naturally by its union with the soul, which is the principle of life; and again, quickened by the soul, the body moves of itself, while a dead body either remains immovable, or is moved only by an exterior power:* so is man's will alive, when conjoined by a right intention with its last end, which is its object and, as it were, its form; and in thus cleaving by love to God and to its neighbour, it is moved by an interior principle of action. But when a right intention of the last end and love is gone, the soul is, as it were, dead, and no longer moves of itself to do any right actions, but either wholly gives over doing them, or is led to do them only by an exterior principle, to wit, the fear of punishment.* Whatever sins therefore stand not with a right intention of the last end and love, are mortal sins: but, so long as these finalities are attended to, any deficiency in point of right order of reason will not be a mortal sin, but venial.
3.139 : Against those who find fault with Vows
3.141 : That a Man's Acts are punished or rewarded by God