All vices are for a time; for they are excited for the present. The impetuosity of anger is appeased when vengeance has been taken; the pleasure of the body puts an end to lust; desire is destroyed either by the full enjoyment of the objects which it seeks, or by the excitement of other affections; ambition, when it has gained the honors which it wished for, loses its strength; likewise the other vices are unable to stand their ground and remain, but they are ended by the very enjoyment which they desire. Therefore they withdraw and return. But virtue is perpetual, without any intermission; nor can he who has once taken it up depart from it. For if it should have any interruption, if we can at any time do without it, vices, which always oppose virtue, will return.

Since, therefore, vices are contrary to virtue, the whole systems must of necessity differ from and be contrary to each other. Because vices are commotions and perturbations of the soul; virtue, on the contrary, is mildness and tranquillity of mind. Because vices are temporary, and of short duration; virtue is perpetual and constant, and always consistent with itself. Because the fruits of vices, that is, pleasures, equally with themselves, are short and temporary, therefore the fruit and reward of virtue are everlasting. Because the advantage of vices is immediate, therefore that of virtue is future.