Such are a few of the different opinions which have been given to the world in regard to the soul. The better to develop them, we shall divide them into two classes. In the one will be found the statements of those philosophers who considered the soul as material; and in the other those of the opposite party, who maintained the doctrine of its immateriality. § 3. Pythagoras and Plato have both maintained the doctrine that the soul was immaterial in its nature; that is, a being existing without aid from the body, and capable of action uncontrolled by any thing corporeal. They hold that all the individual spirits of animals were emanations from the universal Soul of the World, and that these off-givings were incorporeal, immortal, and of the same nature as the pervading Essence itself. They illustrated their doctrine well, by the analogy of a thousand little lights which are all of the same nature as the great flame at which they were kindled. § 4. These philosophers believed that the universe was animated by an immaterial Essence, immortal and invisible, knowing everything, and acting always; and which is the cause of every movement, and the origin of all spirits, these being merely emanations from it. Then, as spirits are very subtle, they cannot unite (they observe) unless they can find a body subtle as the light, or as that expanded air which the vulgar take for heaven. They therefore assume a body less subtle, then another somewhat gross; and thus by degrees they come to be enabled to unite themselves to the bodies of animals, into which they descend as into dungeons or sepulchres. The death of the body, according to them, is the life of the soul, which was in a manner buried, and could only in a feeble way exercise its noblest functions. At the death of the body, the soul shakes off materiality, comes forth of its prison-house, and unites itself to the Soul of the World from which it emanated. According to this opinion then, all the spirits of animals are of the same nature; and the diversity of their functions and faculties arises solely from the difference of the bodies into which they descend. Aristotle supposes an universal intelligence, acting on particular intelligences, as light acts upon the eye; and that as light renders objects visible, so does this universal intelligence render the others intelligent. This philosopher defines the soul as that whereby we live, feel, think, and move; but he is unsatisfactory as to the nature of that Being which is the source of its noblest functions. It is needless, therefore, to search in his writings for a solution of the difficulties which exist upon this subject.