DISORDERED ACTION OF THE EXTERNAL INTELLECT. CHAPTER I. NATURE OF SENSATION AND PERCEPTION. § 34. Remarks on the Nature of Sensation. In accordance with the plan which has been laid down, we proceed to prosecute our inquiries, in the first place, in connexion with the external intellect, or that portion of the intellect which is brought into action in more immediate and intimate proximity with external objects. And under this general head, the first form of intellectual action which presents itself to our notice is that of Sensation. Perhaps it may be proper to remark here, that the term SENSATION has a twofold application. We sometimes use it as expressive of a mental power, and sometimes as expressive merely of the result of the power; in other words, of the mental state or act. The condition, under which this state or act exists, and by which chiefly it is known, is the presence of some external object, operating upon some organ of sense. In other words, a sensation is a simple state of mind, immediately successive to a change in some organ of sense, or at least to a bodily change of some kind, which is caused by the presence of some external body. Accordingly, while we speak of the sensations of heat and cold, of hardness and softness, and the like, we do not ordinarily apply this term to joy and sorrow, hatred and love, and other emotions and passions, which, although they are states of the mind, either simple or complex, originate, nevertheless, under different circumstances. § 35. All Sensation is properly and truly in the Mind. In order to understand more fully the nature of sensation, we may properly advert a moment to the common opinion, that sensation has its true position in the body, and actually takes place there, particularly in the organs of sense. The sensation of touch, as people seem to imagine, is in the hand, which is especially regarded as the organ of touch, and is not truly internal; the smell is in the nostrils, and the hearing in the ear, and the vision in the eye, and not in the soul. But it will at once occur that the outward organs of smell, hearing, and vision are nothing more nor less than mere forms and modifications of matter. And that matter, from its very nature, is not and cannot be susceptible of perception and feeling. It would be inconsistent with all our notions of materiality to consider thought and feeling as attributes of it. All we can say with truth and on good grounds is, that the organs of sense are accessory to sensation and necessary to it, but the sensation or feeling itself is wholly in the mind. "A man" (says Dr. Reid) "cannot see the satellites of Jupiter but by a telescope. Does he conclude from this that it is the telescope that sees those stars? By no means; such a conclusion would be absurd. It is no less absurd to conclude that it is the eye that sees, or the ear that hears. The tele scope is an artificial organ of sight, but it sees not. The eye is a natural organ of sight, by which we see, but the natural organ sees as little as the artificial." But we presume it is not necessary to enter much at length into the consideration of this topic. We readily admit the general connexion existing between the body and the mind, and the still more intimate and important connexion existing between the mind and the sensorial organ; but we should carefully guard against the admission of views which seem to imply, what is a very differing thing, the sameness or identity of the mind with any mere material modification. § 36. Of the Actual Process in cases of Sensation. But while we admit the existence of an intimate connexion between the action of the mind and the antecedent action of some physical organ in all cases of sensation, we do not deny that there is, in some respects, a degree of obscurity attending it. haps all we can say with safety in the matter is this. Per Some object capable of affecting the outward organ must first be applied to it in some way, in consequence of which a modification or affection of the organ actually takes place. Subsequently to the change in the organ, either at its extremity and outward development, or in the brain, with which it is connected, and of which it may be considered as making a part, a change in the mind, or a new state of the mind, immediately takes place. In the statement so far we are sustained by acknowledged facts. But when we inquire how it is, or why it is, that a new state of a material organ causes a new state of the mind; or, in other words, that an affection of the mind naturally and necessarily follows an affection of some part of the body, we touch upon one of those ultimate limits of intellectual action which seem to reject any farther analysis. All we know, and all we can state with confidence, is the simple fact that a mental affection is immediately subsequent to an affection or change, which is physical. It is in this way that we find ourselves constituted. Such is the appointment of the Being who has made us. § 37. Of the Meaning and Nature of Perception. As intimately connected with the subject of Sensation, we now proceed to that of Perception. Sensation and Perception (we speak now, it will be noticed, of external, and not of internal perception) have much in common with each other.-Perception, using the term in its application to outward objects, differs from sensation as a whole does from a part. It embraces more. It may be defined, therefore, an |