BOOK IV.-CHAPTER I.

Of our Acquired Perceptions, and the Metaphysics of Vision.

LET us return back, for a few moments, upon our footsteps, and retrace the progress of our primitive man or philosopher, in attaining the first elements of human knowledge. We have seen that the number of his original perceptions would be extremely limited, and that he would be utterly unable to determine from what kinds of objects they were derived. By sight he would perceive, at first, only a variously coloured superficies, but of figures, distances and magnitudes would know nothing. By the ear he would distinguish sounds with their several tones and degrees of intensity, while he was ignorant of the causes from which they proceed; and by smell the variety of odours which were wafted to that sense. * All this time, however, he would be acquainted only with himself and his own sensations? His ac

* Dr. Reid in chap. 6, sect. 8, of his Treatise on the Human Mind; says, "if we should suppose that smell and sound were conveyed in right lines from the objects, and that every sensation of hearing and smell sug. gested the precise direction or position of its object; in this case, the operations of hearing and smelling would be similar to those of seeing; we should smell and hear the figure of objects in the same sense as now we see it; and every smell and sound would be associated with some figure in the imagination, as colour is in our present state." We should smell and hear the figure of objects!! Would not this be to outstrip Don Quixotte himself, renowned as he was for his exploits, who never pretended to any thing more than having seen his Dulcinea by hearsay?

quaintance with the objects around him would soon commence, and curiosity, as well as enjoyment, would prompt. him to extend it. Subjecting the things which presented themselves to his sight to the examination of his touch, he would discover that, instead of exhibiting to him any longer only a plain surface variously coloured, they were formed in different figures, and situated at different distances. Marking the appearances which objects displayed to the sight, when thus examined by the sense of touch, and taking these appearances as the signs by which to designate and distinguish them in future, after repeated attempts, he would be able to perceive their figures and magnitudes by sight alone. This process by which the mind arrives at a perception of figures, magnitudes and distances, is what the young man couched by Cheselden, very significantly denominated learning to see. Suppose, for instance, the case proposed by Molineux to Mr. Locke, of a globe and a cube being placed before the young man just mentioned, immediately upon his receiving sight, and it is evident, as determined by Mr. Locke, that he would not, at first, distinguish the one from the other. But after examining them both by the help of touch, and discovering their real figures, and marking at the same time with attention the peculiar appearance which each presented to the eye; that appearance, whenever it was again presented, would become the sign by which the thing signified, whether the globe or cube, would be known. This method of procedure of the understanding in obtaining its acquired perceptions, may, without a figure of speech, be styled the interpretation of signs. The same thing happens in the case of hearing, smelling, taste, and all the senses. They have their lessons to acquire by experience and observation, as well as the sight. At first we are sensible only of the sensations, which sounding bodies occasion in us, according to their different modifications and various degrees of intensity; afterwards by habit and attention we learn to distin

guish the objects from which they proceed, as well as to re lish the higher pleasures of concord and harmony. Thus the variety of sounds also become so many signs, by which their several notices are conveyed into the understanding, and objects discriminated from each other. We distinguish every day instantaneously, and without any effort of mind, the voices of the different persons with whom we are in habits of intimacy, the noises which are occasioned by thunder, cannon or fire-arms, that of the various vehicles of conveyance which pass by our doors, and numberless others of a similar nature, These are none of them original, but acquired perceptions, Hence it is both with sight and hearing, that they become liable to such an indefinite number of mistakes and delusions. For, whenever, either by art and contrivance, or from mere contingency, the sign by which certain objects are exhibited to the mind, can be presented, the objects themselves will appear to be present. Thus, for example, after our primitive man had learned to distinguish a globe by his sight from its peculiar appearance, if the painter had placed in his view a globe drawn in a picture, he would have imagined it to be a real globe, and expected that it would seem such to his sense of touch. We find that the young man couched by Cheselden, discovered his surprise that those things in a picture which seemed to have bulk to his sight, were not found to have it when touched: and showed his astonishment by asking which of his senses it was that deceived him. In this power of deceiving the sense of sight, meaning by the term deception the presentation of the mere signs of things, and not the very things themselves, consists the painter's art; as in deceptions of the ear by the various modulations of sound, consists the whole power of the ventriloquist. This view of the subject, will serve also to explain what appears to most persons to be an unaccountable phenomenon of the human mind; viz. that when we are deprived of one of our senses, the others, it is said, become more acute, and convey to us

a greater number of perceptions, or more extensive infor mation; insomuch that some persons who are blind, are known to be able to distinguish colours by the touch, and to become much more acute and nice than other men in their discrimination of sounds. There is no necessity, however, in order to explain this fact, to have recourse to the vulgar solution, which supposes, that when we are deprived of one of our senses, greater vigour is communicated to the rest, since this is a mere gratuitous assumption, unsupported by proof or probability. The phenomenon is readily accounted for by adverting to the circumstance, that when we are divested of one of the senses, it becomes indispensably necessary, in order to attain that information in regard to the objects around us which men so eagerly pursue, to attend to all the nicest and most delicate perceptions of the others. A man, for instance, who is deprived of sight, being cut off from all those interesting notices conveyed into the mind by that organ, and anxiously desirous of obtaining those ideas which he found prevalent among others, would exert himself to the utmost to supply the deficiency; and in order to this end, would closely and minutely attend to all those delicate perceptions of touch, which would pass unnoticed by him were he able to arrive at this intelligence from any other quarter. Hence, although he can have no idea of colours, by the nicety of his observations, he will learn to distinguish cloths of the different colours by his touch alone, as well as to conduct himself by this sense from place to place, with considerable ease and safety. The young man couched by Cheselden, complained, after he had gained his sight, that he was losing the faculty of walking in the dark. This was the natural result of the change in his condition; for having now obtained possession of the higher power of sight, he found it no longer necessary to pay attention to those perceptions of touch by which he had been formerly directed, and they passed entirely unnoticed. Thus we perceive, that from the very first moments

of infancy, when we open our eyes to admit the light, we are placed in a state of pupilage to nature; and from her as our instructress, while as children we are pursuing our innocent sports and gambols, are deriving insensibly to ourselves, the most sublime and important lessons. It is a very common observation, that children learn more during the first two years of their lives, than in any equal portion of time afterwards, and we can now enter fully into that view of the subject, and feel how philosophically just and true the opinion is. Every time the child, the little pupil of nature, opens its eyes, listens to a sound, pursues an object of desire, moves its limbs, or lisps an articulate sound, it is imbibing the most important and useful instruction. Let us leave our children, then, to the enjoyment of that license and freedom from restraint in this first stage of life, which their Creator evidently intended, to follow their native impulses, and seek the gratification of all their innocent desires. Those indolent mothers who, in order to save themselves the trouble of paying attention to them, put them under the care of mistresses, where, even before their infant faculties begin to unfold themselves, they are constrained to pore over lessons which are rendered irksome and disgusting, only because prematurely urged upon them, their little limbs constrained and their growth impeded, their minds tortured with the fear of punishment, and their health impaired by unnatural constraint, are as violently thwarting the benevolent purposes of nature, as outraging the feelings and wishes of their offspring. Such forced and premature instruction may become the cause of very serious evils and inconveniences to the rising generation, but can never be productive of any useful consequences. As those parents, who have the justest views of human nature, will never suffer themselves to be too much elated with discovering in their children a remarkable precocity of genius, since such precocity scarcely ever realizes the expectations it excites; so those who have the most cor