LITMIR.BIZ

      CHAPTER IV.

       THE NEW PHILOSOPHY.

       Table of Contents

I

       Table of Contents

      It is a common prejudice to treat Voltaire as if he had done nothing save write the Pucelle and mock at Habakkuk. Every serious and instructed student knows better. Voltaire's popularisation of the philosophy of Newton (1738) was a stimulus of the greatest importance to new thought in France. In a chapter of this work he had explained with his usual matchless terseness and lucidity Berkeley's theory of vision. The principle of this theory is, as every one knows, that figures, magnitudes, situations, distances, are not sensations but inferences; they are not the immediate revelations of sight, but the products of association and intellectual construction; they are not directly judged by vision, but by imagination and experience. If this be so, neither situation, nor distance, nor magnitude, nor figure, would be at once discerned by one born blind, supposing him suddenly to receive sight. Voltaire then describes the results of the operation performed by Cheselden (1728) on a lad who had been blind from his birth. This experiment was believed to confirm all that Locke and Berkeley had foreseen, for it was long before the patient could distinguish objects by size, distance, or shape.[61] Condillac had renewed the interest which Voltaire had first kindled in the subject, by referring to Cheselden's experiment in his first work, which was published in 1746.[62]

      It happened that in 1748 Réaumur couched the eyes of a girl who had been born blind. Diderot sought to be admitted to the operation, but the favour was denied him, and he expressed his resentment in terms which, as we shall see, cost him very dear. As he could not witness the experiment, he began to meditate upon the subject, and the result was the Letter on the Blind for the Use of those who See. published in 1749—the date, it may be observed in passing, of another very important work in the development of materialistic speculation, David Hartley's Observations on man, his frame, his duty, and his expectations. Diderot's real disappointment at not being admitted to the operation was slight. In a vigorous passage he shows the difficulties in the way of conducting such an experiment under the conditions necessary to make it conclusive. To prepare the born-blind to answer philosophical interrogatories truly, and then to put these interrogatories rightly, would have been a feat, he declares, not unworthy of the united talents of Newton, Descartes, Locke, and Leibnitz. Unless the patient were placed in such conditions as this, Diderot thinks there would be more profit in questioning a blind person of good sense, than in the answers of an uneducated person receiving sight for the first time under abnormal and bewildering circumstances.[63] In this he was undoubtedly right. If the experiment could be prepared under the delicate conditions proper to make it demonstrative evidence, it would be final. But the experiment had certainly not been so prepared in his time, and probably never will be.[64]

      Read in the light of the rich and elaborate speculative literature which England is producing in our own day, Diderot's once famous Letter on the Blind seems both crude and loose in its thinking. Yet considering the state of philosophy in France at the time of its appearance, we are struck by the acuteness, the good sense, and the originality of many of its positions. It was the first effective introduction into France of these great and fundamental principles; that all knowledge is relative to our intelligence, that thought is not the measure of existence, nor the conceivableness of a proposition the test of its truth, and that our experience is not the limit to the possibilities of things. That is an impatient criticism which dismisses the French philosophers with some light word as radically shallow and impotent. Diderot grasped the doctrine of Relativity in some of the most important and far-reaching of all its bearings. The fact that he and his allies used the doctrine as a weapon of combat against the standing organisation, is exactly what makes their history worth writing about. The standing organisation was the antagonistic doctrine incarnate. It made anthropomorphism and the absolute the very base and spring alike of individual and of social life. No growth was possible until this speculative base had been transformed. Hence the profound significance of what looks like a mere discussion of one of the minor problems of metaphysics. Diderot was not the first to discover Relativity, nor did he establish it; but it was he who introduced it into the literature of his country at the moment when circumstances were ripe for it.

      Condillac, as we have said, had published his first work, the Essay on the Origin of Human Knowledge, three years before (1746). This was a simple and undeveloped rendering of the doctrine of Locke, that the ultimate source of our notions lies in impressions made upon the senses, shaped and combined by reflection. It was not until 1754 that Condillac published his more celebrated treatise on the Sensations, in which he advanced a stride beyond Locke, and instead of tracing our notions to the double source of sensation and reflection, maintained that reflection itself is nothing but sensation "differently transformed." In the first book, again, he had disputed Berkeley's theory of vision: in the second, he gave a reasoned adhesion to it. Now Diderot and Condillac had first been brought

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