happily the doctrine of Locke, that it becomes its indispensable crown. Condillac, at first, repulsed this hypothesis. He maintained, in his Essai sur l'Origine des Connaissances humaines, that the eye appreciates, naturally, figures, magnitudes, situations, and distances. But he retracted afterwards, in his Traité des Sensations, and adopted the hypothesis of the education of the eye by the touch. He so fully adopts it, that he even attempts to appropriate it to himself; for this celebrated Treatise on Sensations is, at bottom, only an impudent plagiarism from the work of Berkeley, whose name, I believe, is not even once cited. As to Voltaire, the curious and eager importer of the discoveries of our neighbours, he was among the first to admit these singular novelties; and in his Philosophie de Newton, he asserts the truth of the English theory, with the same zeal he had displayed for Attraction. 'It is absolutely necessary to conclude,' says he in this work (Chapter VII.), that distance, magnitude, situations, are not, strictly speaking, visible things; that is, they are not proper and immediate objects of sight. The proper and immediate object of sight is nothing but colored light; all else we perceive only in the long run, and by experience. We learn to see, precisely as we learn to read; the difference is merely that the art of seeing is the easier to learn, and that nature is equally in all men the teacher. The sudden judgments, very nearly uniform, which all minds, at a certain age, form respecting distances, magnitudes, situations, lead us to suppose that we have only to open our eyes, in order to see precisely as we do see. this is a mistake. The aid of other senses is necessary. If we had only the sense of sight, we should have no means of knowing extension in length, breadth, or depth; and a pure spirit could never know them, unless God revealed them to him.' 66 But It must be confessed, that this eighteenth century, so admirable in many respects, has shown on this point, as on several others, a singular simplicity in the midst of its incredulity. Here is a man who adopts an opinion the most opposed to the common and universal sentiment of mankind, with a faith which may, under other relations, well recall to mind epochs the most credulous. "But what! has not the theory you reject been demonstrated by a celebrated and undeniable experiment? Do you forget the blind boy of Cheselden? Has not that experiment, in 1729, established, point by point, all the predictions of Berkeley, twenty years after the publication of his Essay? Is not this one of the best known, most striking, and oftenest cited facts in the history of science and philosophy ? "We shall speak elsewhere (in the article on VISION) of this celebrated experiment; it will suffice us to say here, that the account given of it has been almost always altered to make it quadrate with the demands of the theory; that the original narration in the Philosophical Transactions is very little conclusive, and full of absurdities and contradictions; and that, when carefully examined, it makes rather against Berkeley, than in his favor. The boy operated on for a cataract did by no means see objects inverted. Moreover, he distinguished them so well, says the account, one from another, that he preferred those of a uniform and regular figure. All that the account proves is, merely that vision in the diseased person was very difficult to be established, as was to be supposed in pathological cases of this kind. Has it not often. been remarked in persons who have a long time been deprived of the sight of one eye, that the nerve corresponding to that eye is affected with atrophy? What completes the demonstration of the little reliance to be placed on the inductions from this experiment, is the manner in which it terminated. The blind boy had been operated upon, at first, only in the case of one eye; at the end of a year, the cataract was taken from the other eye. During this year he had educated sight by touch; that is, according to the hypothesis, he had been able to apply the notions of extension, suggested by touch, to the colored sensations which were given him by the eye which had been operated on. He should then have immediately seen, in the full sense of the term, with his second eye, as soon as it was uncovered. But, however, it was not so, and he was obliged, they say, to recommence a new education, as in the case of the first: that is, in our view, the pathological state demanded in the case of this eye, as in that of the first, a certain time for its cure. "It is on such an experiment, which no other operation for the cataract, among innumerable cases, has confirmed, and which, on the contrary, other accounts of similar operations constantly belie, that is still to-day affirmed, and taught, Berkeley's Theory of Vision, grossly perverted by the other disciples of Locke! But, instead of the blind boy of Cheselden, have we not around us all this multitude of beings which come each day to the light, and can we not experiment on them, with some little assurance, whether, in point of fact, sight is a natural faculty, or whether it is merely the result of touch and experience? The examination of the smallest animal might, one would suppose, suffice to prevent us from being betrayed into this wild aberration, into which science has devi ated with so much assurance for more than this hundred years. * "My friend, the late Dr. Bertrand, in a thesis directed against the doctrine still taught in the schools, has shown how all nature protests, by all that she offers to our view, against this strange assertion, that sight is, as to notions of extension, only a blind sense, and that it is touch which teaches us to see. Do we see young animals rushing at hazard against obstacles? Is it experience, that teaches the chicken to make the movement necessary to pick up with its beak the grain that must feed it, and which its eye sees without previous education? The young quail, just hatched, and still encumbered with the remains of its shell, pursues the insect which it must make its prey. The child sees, at a period when it has as yet touched nothing; it has no need to run its fingers over all the parts of the face of its nurse to recognize her and smile. Birds are of all animals those which appear to enjoy the most perfect vision; and yet they are precisely those least fitted to learn to see, for they cannot be said, properly speaking, to have an organ of touch. Is it locomotion, that gives them the ideas of figure, distance, and situation? But do we not see that young birds, when for the first time they come out of their nests, go and alight, without hesitation, on the branches of the neighbouring trees, which they do not take for colors? If their flight is infirm, it is not because their sight is at fault, but because their wings are weak. Their eyes serve very well to direct their first motions; but how could they have learned to see, while remaining, without moving, in the narrow space of their nests?" We have very little to say, ourselves, on this Theory of Vision, or on this slight, but sufficient, refutation of it by M. Leroux. The singular absurdity into which our scientific professors fall, in admitting, with Berkeley, that naturally we do not see objects at all, and yet contending that we see objects naturally inverted, and learn subsequently, by experience, to give them this erect appearance, an absurdity repeated, we believe, in all our schools, we commend to the very careful attention of those who boast of sensation and experiment, and talk of the exact sciences. The present * Examination de l'opinion généralment admise sur le manière dont nous recevons par la vue la connaissance des corps. editor of the North American Review, formerly a teacher of philosophy and metaphysics in Cambridge University, in the volume of Essays already referred to, says: "If metaphysicians were challenged to produce one broad, definite, and fruitful fact in their science, which had been discovered since the time of Bacon, and so established as to admit of neither cavil nor doubt, we know of no better way whereby they could silence the questioner, than by a reference to Berkeley's New Theory of Vision." He proceeds to develope the theory, and to accept it, in a manner as unqualified as could be asked by its most ardent friends. We believe that it is universally accepted among us. But those who read these remarks by M. Leroux, as well as they who study the Theory itself, must see that we cannot accept this theory, without accepting Berkeley's whole doctrine on the non-reality of the external world. Either we must give up the reality of all existence exterior to the me, and recognize only the me and its affections, or we must give up this Theory of Vision. This Theory knocks the philosophy of sensation in the head, and destroys all certainty, save in the case of momentary consciousness. We demand that this be attended to. If they will teach our youth this Theory, we insist that they shall teach it in all its bearings, and in all its legitimate consequences. We protest against the feebleness, not to say dishonesty, of teaching premises, from the consequences of which we shrink. Our youth should be dealt by honestly and fairly, and allowed to be logical and consistent. moral chastity of their natures should not be destroyed by their being compelled to submit to contradictions, and to swallow absurdities. The immorality occasioned by teaching premises, the legitimate conclusions of which must be denied, in order not to revolt common sense, it is not easy to estimate. If your premises lead you to conclusions contrary to the universal sense of mankind, do not deny your conclusions, but reëxam * Bowen's Essays, ubi supra, p. 274. The है ine and correct your premises. All the world has believed that we see because we have eyes, and because we have the power or faculty of vision; and not that we have the power to see, because we have the sense of touch, and see only because we have learned to see. But to return. "We have lingered long on this question of sight, because it is in itself a subject of the greatest importance, and because it is sad to see a false theory taught in scientific treatises, and in our schools; and furthermore, because nothing can better make us perceive the genesis of Berkeley's metaphysical system, or of what is called his Idealism. This idealism, which he opposes, as a preservative, to the materialism proceeding from the school of Locke, and which he presents as a shield to religion against atheists, skeptics, and wits, is itself merely a deduction from Locke's doctrine on sensation. What, in point of fact, according to Locke, is intelligence? A collection or assemblage of sensations; nothing else. Now what can we concede to sensation in regard to the reality of the external world? "We know the external world only by sensation. Sensation is merely a mode of the mind's own existence, a modification of ourselves, a passion of our soul. It does not exist by itself; it exists only in us; or rather, it is we alone who exist and who are affected. Philosophers have never doubted the non-reality of what they call the secondary qualities of bodies. They admit without difficulty, that heat or cold, hardness or softness, sweetness or bitterness, red or blue, &c., exist only in the mind; but they generally regard, as really existing, extension, figure, solidity, weight, motion, rest, what they call the primary qualities of bodies. The ideas of Berkeley on sight, formed after Locke, must needs carry him much farther. In fact, if you comprehend the exposition which we have just made of the Theory of Vision, you will see that sight reveals to us only colors, that is, merely sensible qualities, which exist only in us. Moreover, properly speaking, we see not the same objects that we feel by touch. There is no relation between our sensations of touch and our sensations of sight, any more than there is between objects and the conventional names we give them. "If Berkeley thought this of sight, for a still stronger reason, he must have thought it of hearing, taste, and smell. Touch itself, charged with sustaining the whole edifice of the notions abstracted from the other senses, must in time undergo the |
