Diogenes believed that it was formed of air, from which he has inferred the necessity of breathing, and defines it as an air which passes from the mouth through the lungs to the heart, where it is warmed, and from whence it is distributed through the entire body. Leucippus and Democritus have claimed that it was Fire, as that element is composed of atoms which easily penetrate all parts of the body, and makes it move. Hippocrates has said that it is a composition of water and fire. Empedocles says that it includes the four elements. Epicurus believed like Democritus, that the soul is composed of fire, but he adds that in that composition there enters some air, a vapor, and another nameless substance of which is formed a very subtile spirit, which spreads through the body and and which is called the soul. VII. Not to shuffle, as all these philosophers have done, and to have as perfect an idea as is possible of the souls of animals, let us admit that in all, without excepting man, it is of the same nature, and has no different functions, but by reason of the diversity of organs and humors; hence we must believe what follows. It is certain that there is in the universe a very subtile spirit, or a very delicate matter, and always in motion, the source of which is in the Sun, and the remainder is spread in all the other bodies, more or less, according to Nature or their consistency. That is the Soul of the Universe which governs and vivifies it, and of which some portion is distributed among all the parts that compose it. This Soul, and the most pure Fire which is in the universe does not burn of itself, but by the different movements that it gives to the particles of other bodies where it enters, it burns and reflects its heat. The visible fire has more of this spirit than air, the latter more than water, and the earth much less than the latter. Among the mixed bodies, plants have more than minerals, and animals more than either. To conclude, this fire being enclosed in the body, it is rendered capable of thought, and that is what is called the soul, or what is called animal spirits, which are spread in all parts of the body. Now, it is certain that this soul being of the same nature in all animals, disperses at the death of man in the same manner as in other animals, from whence it follows that what Poets and Theologians sing or preach of the other world, is a chimera which they have invented, and which they narrate for reasons that are easy to guess. OF SPIRITS WHICH ARE CALLED DEMONS. I.