421. (17) Love or the will is defiled in the understanding and by it, if they are not elevated together. This is because love, if not elevated, remains impure (as stated above, n. 419, 420); and while it remains impure it loves what is impure, such as revenges, hatreds, deceits, blasphemes, adulteries, for these are then its affections that are called lusts, and it rejects what belongs to charity, justice, sincerity, truth, and chastity. Love is said to be defiled in the understanding, and by it; in the understanding, when love is affected by these impure things; by the understanding, when love makes the things of wisdom to become its servants, and still more when it perverts, falsifies, and adulterates them. Of the corresponding state of the heart, or of its blood in the lungs, there is no need to say more than has been said above (n. 420), except that instead of the purification of the blood its defilement takes place; and instead of the nutrition of the blood by fragrant odors its nutrition is effected by stenches, precisely as it is respectively in heaven and in hell.