567. There are two sources of heat, one from the Sun of heaven which is the Lord, and the other from the sun of the world. The heat that is from the Sun of heaven, that is, the Lord, is spiritual heat; and this in its essence is love (see above, n. 126-140); but the heat from the sun of the world is natural heat, and this in its essence is not love, but serves spiritual heat or love as a receptacle. It can be established that love in its essence is heat by reason of the warming of the mind (animus) and of the body thereby, as a result of love in accord with its degree and quality, and this man experiences in the winter as well as in the summer. The warming of the blood is from the same source. That the natural heat that comes into existence from the sun of the world serves spiritual heat as a receptacle is evident from the heat of the body, which is excited by the heat of its spirit, and is a kind of substitute for that heat in the body. It is especially evident from the spring and summer heat in animals of every kind which then annually renew their loves. [2] It is not the natural heat that does this, but it disposes their bodies to receive the heat that flows into them from the spiritual world; for the spiritual world flows into the natural as cause into effect. Whoever believes that natural heat produces these loves is much deceived, for there is an influx from the spiritual world into the natural world, and not from the natural world into the spiritual; and as all love belongs to the life itself it is spiritual. [3] Again, he who believes that anything comes into existence in the natural world without influx from the spiritual world is deceived, for what is natural comes into and remains in existence only from what is spiritual. Furthermore, the subjects of the vegetable kingdom derive their germinations from influx out of the spiritual world. The natural heat of springtime and summer merely disposes the seeds into their natural forms by expanding and opening them so that influx from the spiritual world can there act as a cause. These things have been brought forward that it may be known that there are two kinds of heat, namely, spiritual heat and natural heat; and that spiritual heat is from the Sun of heaven and natural heat from the sun of the world, and that influx and consequent cooperation produce the effects that appear before the eyes in the world.# # There is an influx from the spiritual world into the natural world (n. 6053-6058, 6189-6215, 6307-6327, 6466-6495, 6598-6626). There is also an influx into the lives of animals (n. 5850). And into the subjects of the vegetable kingdom (n. 3648). This influx is a continual endeavour to act in accordance with the Divine order (n. 6211 at the end).