The foregoing observations may be regarded as a slight introduction to a passage on the connexion between the mind and body, well worthy of especial consideration: "In considering the connexion between the mind and the body, it is of the highest importance always to remember that the mind, or rather the being which thinks and wills, is the active agent. The body, with all its beautiful and wondrous adaptations, only supplies the means of perception and of acting. Nerve-matter is the evident medium and instrument of the being that perceives and acts through it. Physiologists appear to have demonstrated that an imponderable principle, akin to electricity, is evolved in the nervous system, and that currents of this kind are constantly traversing the different sets of nerves, according to their office and function, either as the medium of sensation, volition, or of vegetative life. There is, in short, an action going forward in all the nerves and their centres similar to the electro-magnetic, and, consequently, every nerve is polarized. The soul appears to operate upon these electro-magnetic currents, and to be impressed by them. The _imponderable energia_ passing in these currents, is apparently the medium between the soul and the more palpable materials forming the body. This may be inferred from the fact, that whatever alters the force of these currents, alters the condition of the mind in relation to the body. Thus, the arrest of the current in a nerve, subservient to voluntary muscular action, whether by chemical or mechanical means, prevents the mind from exercising will in the use of the muscle, with which the nerve experimented on is connected. The same occurs, also, in the like case with any nerve through which we obtain sensation of the presence of any body, which, in a natural state, would so affect the body as to produce feeling.