Dicearchus, Asclepiades, and Galienus, have also, to a certain extent, believed that the soul was immaterial, but in a different way from that already alluded to. They suppose that the soul is nothing else than the harmony of all the parts of the body: that is, the result of an exact blending of its elements and disposition of its parts, its humours, and its essences. Thus, they say, as health is not a part of that which is healthy, although it is connected with it, so neither is the soul a part of the animal, although it be within it, but simply the harmony of all those parts which go to form the containing body. On these opinions we must, remark, that their defenders believe in the immateriality of the soul on self-contradictory principles; for to maintain that, the soul is not a body, but merely something inseparably attached to a body, is to say that it is corporeal. We not only term that corporeal which is a body, but everything which has form and accident, and which cannot be separated from matter. Such are the opinions of those philosophers who maintain that the soul is incorporeal or immaterial. We see that they are discordant and contradictory to each other, and consequently little to be heeded as points of faith. We now come to the opposite party, who have upheld the doctrine of its materiality. § 5. Diogenes believed that the soul was composed of air, whence he deduces the necessity of respiration. He defines it as an air which passes through the mouth into the pulmonary vessels, whence it becomes warm, and whence it is distributed to every part of the system. Leucippus and Democritus assert that it is fire, and that, like fire, it is composed of atoms which readily penetrate all parts of the body, and communicate motion to it. Hippocrates said that it was composed of water and of fire. Empedocles thought that it was compounded of the four elements. Epicurus believed with Democritus that the soul is composed of fire, but he adds that there enter into its composition, air, a vapour, and an indescribable substance, which is the principle of thought. Out of these four different substances he makes to himself a very subtle spirit, pervading all the body, and which, he says, we ought to term the soul. Descartes reasons also, but in a very wretched manner, that the soul is not material. I say in a very wretched manner, for never did philosopher reason so badly on this subject as did this great man. Here is his argument. He sets outs by saying that he must doubt in the existence of his own body, believing that there exists no such thing as a body at all, and then he reasons in this fashion: "There exists no body; I exist nevertheless: I am therefore not a body, and consequently I can only be a substance which thinks." Although this fine reasoning destroys itself sufficiently, I will yet take the liberty of giving my opinion of it in two words.