As motion only can result from motion, so life can only result from life. The vital actions of all animals originate in those of their parents, from whom they are detached precisely when their actions become sufficiently independent of them. I am convinced it is upon this principle, that the egg is detached from the ovary and the fœtus from the uterus, as well as because, in these cases, the ovary and the uterus themselves, after long quiescence, recover an independent action of their own. The same power which enables an organic body to act by itself, forces it to separate from another. Life then seems, in a great measure, to consist in the successive attraction and repulsion of particles—properties equally common to minerals, vegetables and animals, though in different manners and degrees. Life, however, is not here to be confounded with sensibility, which nevertheless I shall afterwards shew is also possessed by all of them. Life seems inseparable from generation, nutrition and decay, or, in other words, from origin, increase, diminution—a progression which minerals and vegetables pass through as well as animals. Minerals also increase by additions to their external surfaces, vegetables by absorbing from without inward, and animals by absorbing from their internal as well as external surfaces. * * * * * By the intellectual functions, I understand the actions of the intellectual organs, or, in other words, those actions which constitute mind. With soul—the sacred and revered province of theologians, I do not wish in the slightest degree to interfere; not for the harsh reason assigned by atheists, namely, that the whole empire of ignorance, the direction of the basest passions, and the gun or bayonet of the soldier are under their command (these are sentiments which I never shall profess), but for a juster and a better reason, namely this, that soul is, in truth, their proper province. Sensation, then, seems to be entirely dependent on touch, which, in the other senses, is only modified so that one receives one kind of it, and another receives another; thus the tongue is touched by means of liquids, the nose by means of odours, the ear by aeriform vibrations, and the eye by light. All the other intellectual functions are nevertheless mere modifications of sensation. Upon them, therefore, we shall not dwell, but, by taking into view some important facts in anatomy, which have a relation to all of them, I shall be able to explain sensation in particular.