32. Further, it will now be explained how faith is formed from charity. Every man has a natural mind and a spiritual mind, a natural mind for the world and a spiritual mind for heaven. Man as to understanding is in both; but not as to his will before he shuns and turns himself away from evils as sins. When he does this, his spiritual mind is then opened with respect to the will also; and when it has been opened, there flows from it into the natural mind spiritual heat from heaven. This heat in its essence is charity and it gives life to the cognitions of truth and good which are in the natural mind, and out of them it forms faith.
This is similar to what takes place in a tree. It does not receive vegetative life before heat from the sun flows in and unites with light, as happens in the spring time. There is, moreover, a full parallel between the quickening of man with life and the vegetation of a tree in this respect, that the latter is effected by the heat of this world, and the former by the heat of heaven: for this reason also man is so often likened to a tree by the Lord.