90. Since angels are spiritual they can live in no other than spiritual heat and light, while men can live in no other than natural heat and light; for what is spiritual accords with what is spiritual, and what is natural with what is natural. If an angel were to derive the least particle from natural heat and light he would perish; for it is totally discordant with his life. As to the interiors of the mind every man is a spirit. When he dies he withdraws entirely from the world of nature, leaving behind him all its belongings, and enters a world where there is nothing of nature. In that world he lives so separated from nature that there is no communication whatever by continuity, that is, as between what is purer and grosser, but only like that between what is prior and posterior; and between such no communication is possible except by correspondences. From this it can be seen that spiritual heat is not a purer natural heat, or spiritual light a purer natural light, but that they are altogether of a different essence; for spiritual heat and light derive their essence from a sun which is pure Love, and this is Life itself; while natural heat and light derive their essence from a sun which is pure fire, in which (as said above) there is absolutely nothing of life.