solicitations of pleasure and have no experience of pain, would be to place us where injuries would meet us at every step and in every motion, and whether felt or not, would be destructive to life. To suppose that we are to move and act without experience of resistance and of pain, is to suppose not only that man's nature is changed, but the whole of exterior nature also— there must be nothing to bruise the body or hurt the eye, nothing noxious to be drawn in with the breath in short, it is to imagine altogether another state of existence, and the philosopher would be mortified were we to put this interpretation on his meaning. Pain is the necessary contrast to pleasure: it ushers us into existence or consciousness: it alone is capable of exciting the organs into activity: it is the companion and the guardian of human life.

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CHAPTER VIII.

OF THE SENses generalLY, INTRODUCTORY TO THE SENSE OF TOUCH.

ALTHOUGH We are most familiar with the sensibility of the skin, and believe that we perfectly understand the nature of the impressions upon it and the mode of their conveyance to the sensorium, yet there is a difficulty in comprehending the operations of all the organs of the senses a difficulty not removed by the apparent simplicity of that of touch.

There was a time when the enquirer was satisfied on finding that in the ear there was a little drum and a bone to play upon it, with an accompanying nerve. This was deemed a sufficient explanation of the organ of hearing. It was thought equally satisfactory if in experimenting upon the eye, the image was seen painted at the bottom of it on the surface of the nerve. But although the impression be thus traced to the extremity of the nerve, still we comprehend nothing of the nature of that impression, or of the manner in which it is transmitted to the

sensorium. To the most minute examination, the nerves, in all their course, and where they are expanded into the external organs of sense, seem the same in substance and in structure. The disturbance of the extremity of the nerve, the vibrations upon it, or the images painted upon its surface, cannot be transmitted to the brain according to any physical laws that we are acquainted with. The impression on the nerve can have no resemblance to the ideas suggested in the mind. All that we can say is, that the agitations of the nerves of the outward senses are the signals, which the Author of nature has made the means of correspondence with the realities. There is no more resemblance between the impressions on the senses and the ideas excited by them, than there is between the sound and the conception raised in the mind of that man who, looking out on a dark and stormy sea, hears the report of cannon, which conveys to him the idea of despair and shipwreck-or between the impression of light on the eye, and the idea of him who, having been long in terror of national convulsion, sees afar off a column of flame, which is the signal of actual revolt.

By such illustrations, however, we rather show the mind's independence of the organ of sense, and how a tumult of ideas will be excited by an impression on the retina, which, notwith

standing, may be no more intense than that produced by a burning taper. They are instances of excited imagination. But even the determined relations which are established in a common act of perception between the sensation and the idea in the mind, have no more actual resemblance. How the consent, which is so precise and constant, is established, can neither be explained by anatomy nor by physiology nor by any mode of physical inquiry whatever.

From this law of our nature, that certain ideas originate in the mind in consequence of the operation of corresponding nerves, it followsthat one organ of sense can never become the substitute for another, so as to excite in the mind the same idea.

When an individual is deprived of the organs of sight, no power of attention, or continued effort of the will, or exercise of the other senses, can make him enjoy the class of sensations which is lost. The sense of touch may be increased in an exquisite degree; but were it true, as has been asserted, that individuals can discover colours by the touch, it could only be by feeling a change upon the surface of the stuff and not by any perception of the colour. It has been my painful duty to attend on persons who have pretended blindness and that they could see with their fingers. But I have ever found that

by a deviation from truth in the first instance, they have been entangled in a tissue of deceit ; and have at last been forced into admissions which demonstrated their folly and weak inventions. I have had pity for such patients when they have been the subjects of nervous disorders which have produced extraordinary sensibility in their organs-such as a power of hearing much beyond our common experience; for it has attracted high interest and admiration, and has gradually led them to pretend to powers greater than they actually possessed. In such cases it is difficult to distinguish the symptoms of disease, from the pretended gifts which are boasted of.

: Experiment proves, what is suggested by Anatomy, that not only the organs are appropriated to particular classes of sensations, but that the nerves, intermediate between the brain and the outward organs, are respectively capable of receiving no other sensations but such as are adapted to their particular organs.

Every impression on the nerve of the eye, or of the ear, or on the nerve of smelling, or of taste, excites only ideas of vision, of hearing, of smelling, or of tasting; not solely because the extremities of these nerves, individually, are suited to external impressions, but because the nerves are, through their whole course and wherever they are irritated, capable'

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