3. Some idea of love as being the life of man can be had by considering the sun's heat in the world. It is well known that this heat is a kind of common life of all forms of the earth's vegetation. For from this heat, as happens when it goes forth in springtime, plants of every kind rise out of the ground, are adorned with leaves, afterwards with flowers, and at last, with fruits, and thus in a sense they live. But when the heat recedes, as happens in the autumn and winter, the plants are stripped of these signs of their life and they wither. It is the same with love in man, for heat and love mutually correspond. For that reason also, love is warm.