I. Common observation, the spontaneous course of our reflections, our instinctive interpretation of nature, reveal to us matter, motion, and intelligence, as the co-existing phenomena of the universe. In the farthest distances of space cognisable to our senses, we discern matter and motion, and their subordination to intelligence. Upon the earth’s surface we discern, in the finely designed mechanism of each plant, the agency of life; and we recognise in the microcosm of each animal a living organization, fitted to be the recipient of individual consciousness, or of personal being. II. The intelligence which is communicated to living beings becomes, to a great extent, dependent upon the organization with which it is combined. Thus every mental faculty is found to have its definite seat and habitat in the bodily frame. The principal successes of modern physiologists have been achieved in determining with what precise parts of the nervous system each affection of consciousness is functionally associated. Different classes of nerves are found to be appropriated to sensation and volition; different parts of the spinal cord are proved to minister to different offices; and of the subdivisions of the brain, each is thought to correspond with a separate faculty, or sentiment, or appetite. So far the mental forces, or operations of a living human being, may be conceived to be essentially esoneural, (εσω νευζον.) Each appears to have its proper and special workshop or laboratory in the nervous system. III. But there are not wanting facts which make it reasonable to think that our mental forces or operations transcend occasionally and partially the limits of our corporeal frame. The phenomena adverted to in the preceding letter, in connexion with the narrative of Zschokke’s seer-gift, hardly seem to admit of explanation on any other supposition. Nor is it a very improbable conjecture, that phenomena of the same class form, as it were, the complements of many ordinary esoneural operations. Possibly in common perception the mind directly reaches the object perceived, being excited thereto by the antecedent material impressions on our organs, and the sensations which follow. To denote mental phenomena of the kind I am supposing, I propose the term exoneural, (εξω νευζον.) I venture even, following out this idea, to conjecture further, that the Od force may somehow furnish the dynamic bridge along which our exoneural apprehension travels. IV. The affections of consciousness would thus be in part esoneural, in part exoneural, during the healthy and normal state of our being; the esoneural part being executed in immediate connexion with its appropriate organ, and every manifestation of it being attended with a physical change in the latter.