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. 422. (18) Love, when purified by wisdom in the understanding, becomes spiritual and celestial. Man is born natural, but in the measure in which his understanding is raised into the light of heaven, and his love conjointly is raised into the heat of heaven, he becomes spiritual and celestial; he then becomes like a garden of Eden, which is at once in vernal light and vernal heat. It is not the understanding that becomes spiritual and celestial, but the love; and when the love has so become, it makes its consort, the understanding, spiritual and celestial. Love becomes spiritual and celestial by a life according to the truths of wisdom which the understanding teaches and requires. Love imbibes these truths by means of its understanding, and not from itself; for love cannot elevate itself unless it knows truths, and these it can learn only by means of an elevated and enlightened understanding; and then so far as it loves truths in the practice of them so far it is elevated; for to understand is one thing and to will is another; or to say is one thing and to do is another. There are those who understand and talk about the truths of wisdom, yet neither will nor practise them. When, therefore, love puts in practice the truths of light which it understands and speaks, it is elevated. This one can see from reason alone; for what kind of a man is he who understands the truths of wisdom and talks about them while he lives contrary to them, that is, while his will and conduct are opposed to them? Love purified by wisdom becomes spiritual and celestial, for the reason that man has three degrees of life, called natural, spiritual, and celestial (of which in the Third Part of this work), and he is capable of elevation from one degree into another. Yet he is not elevated by wisdom alone, but by a life according to wisdom, for a man's life is his love.