Love is warm

DLW 2. What the life of man is, no one knows unless he knows that it is love. If this is not known, one person may believe that man's life is nothing but perceiving with the senses and acting, and another that it is merely thinking; and yet thought is the first effect of life, and sensation and action are the second effect of life. Thought is here said to be the first effect of life, yet there is thought which is interior and more interior, also exterior and more exterior. What is actually the first effect of life is inmost thought, which is the perception of ends. But of all this hereafter, when the degrees of life are considered.

DLW 3. Some idea of love, as being the life of man, may be had from the sun's heat in the world. This heat is well known to be the common life, as it were, of all the vegetations of the earth. For by virtue of heat, coming forth in springtime, plants of every kind rise from the ground, deck themselves with leaves, then with blossoms, and finally with fruits, and thus, in a sense, live. But when, in the time of autumn and winter, heat withdraws, the plants are stripped of these signs of their life, and they wither. So it is with love in man; for heat and love mutually correspond. Therefore love also is warm.
Author: E. Swedenborg (1688-1772).