Selection from Divine Love and Wisdom ~ Emanuel Swedenborg
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, 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. Consequently, so far as his life is according to wisdom, so far he loves wisdom; and his life is so far according to wisdom as he purifies himself from uncleannesses, which are sins; and so far as he does this does he love wisdom.
That love purified by the wisdom in the understanding becomes spiritual and celestial cannot be seen so clearly by their correspondence with the heart and lungs, because no one can see the quality of the blood by which the lungs are kept in their state of respiration.
The blood may abound in impurities, and yet not be distinguishable from pure blood. Moreover, the respiration of a merely natural man appears the same as the respiration of a spiritual man. But the difference is clearly discerned in heaven — for there every one respires according to the marriage of love and wisdom; therefore as angels are recognized according to that marriage, so are they recognized according to their respiration. For this reason it is that when one who is not in that marriage enters heaven, he is seized with anguish in the breast, and struggles for breath like a man in the agonies of death; such persons, therefore throw themselves headlong from the place, nor do they find rest until they are among those who are in a respiration similar to their own; for then by correspondence they are in similar affection, and therefore in similar thought.
From all this it can be seen that with the spiritual man it is the purer blood, called by some the animal spirit, which is purified; and that it is purified so far as the man is in the marriage of love and wisdom. It is this purer blood which corresponds most nearly to that marriage; and because this blood inflows into the blood of the body, it follows that the latter blood is also purified by means of it. The reverse is true of those in whom love is defiled in the understanding. But, as was said, no one can test this by any experiment on the blood; but he can by observing the affections of love, since these correspond to the blood.
(Divine Love and Wisdom 422, 423)