379. People know that a person has in him, and every animal in it, a vital warmth, but they do not know what its origin is. Everyone speaks about it on the basis of conjecture. Consequently those who have known nothing about the correspondence of natural phenomena with spiritual ones have attributed its origin to the warmth of the sun, some to the activity of its particles, and some to life itself, though because they have not known what life is, they have simply substituted this term in speaking of it. On the other hand, one who knows that there is a correspondence of love and its affections with the heart and its derivatives may also know that love is the origin of the vital warmth. For love emanates from the spiritual sun where the Lord is as warmth, and it is also felt by the angels as warmth. This spiritual warmth, which in its essence is love, is what flows by correspondence into the heart and its blood, imparting to it its warmth and at the same time animating it.  The fact that a person grows warm and, so to speak, catches fire in the measure of his love and its intensity, and that he becomes listless and cools in the measure that it wanes, is something people know, for they feel that warmth and see it. They feel it from the warmth present throughout the body, and see it from the flush of the face. And conversely, they feel its extinction from the coldness of the body, and see it from the pallor of the face. Because love is a person's life, therefore the heart is the first and last vessel of that life. Moreover, because love is a person's life, and the soul maintains its life in the body by means of the blood, therefore blood in the Word is called the soul (Genesis 9:4, Leviticus 17:14). What is meant by the soul in its various senses will be told in a subsequent discussion.