379. It is known that there is vital heat in man and in every living creature; but its origin is not known. Every one speaks of it from conjecture, consequently such as have known nothing of the correspondence of natural things with spiritual have ascribed its origin, some to the sun's heat, some to the activity of the parts, some to life itself; but as they have not known what life is, they have been content with the mere phrase. But any one who knows that there is a correspondence of love and its affections with the heart and its derivations may know that the origin of vital heat is love. For love goes forth as heat from the spiritual sun where the Lord is, and moreover is felt as heat by the angels. This spiritual heat which in its essence is love, is what inflows by correspondence into the heart and its blood, and imparts heat to it, and at the same time vivifies it. That a man grows hot, and, as it were, is fired, according to his love and the degree of it, and grows torpid and cold according to its decrease, is known, for it is felt and seen; it is felt by the heat throughout the body, and seen by the flushing of the face; and on the other hand, extinction of love is felt by coldness in the body, and is seen by paleness in the face. Because love is the life of man, the heart is the first and the last of his life; and because love is the life of man, and the soul maintains its life in the body by means of the blood, in the Word blood is called the soul (Gen. 9:4; Levit. 17:14). The various meanings of soul will be explained in what follows.