"The adaptation of the eye to its function is, therefore, most complete, and is seen in the very limits which are set to its defects. Here the result which may be reached by innumerable generations working under the Darwinian law of inheritance, coincides with what the wisest Wisdom may have devised beforehand. A sensible man will not cut firewood with a razor, and so we may assume that each step in the elaboration of the eye must have made the organ more vulnerable and more slow in its development. We must also bear in mind that soft, watery animal textures must always be unfavourable and difficult material for an instrument of the mind.... "But, apparently, we are not yet come much nearer to understanding sight. We have only made one step: we have learnt how the optical arrangement of the eye renders it possible to separate the rays of light which come in from all parts of the field of vision, and to bring together again all those that have proceeded from a single point, so that they may produce their effect upon a single fibre of the optic nerve. "Let us see, therefore, how much we know of the sensations of the eye, and how far this will bring us towards the solution of the problem." P. 226, seq. From the Professor's mention of "much bolder and more paradoxical conclusions," the final result of his next inquiry may be anticipated. Sensation is so far from making evident the truth of our visual knowledge that it increases our perplexities tenfold. "The inaccuracies," he tells us, "and imperfections of the eye as an optical instrument, and those which belong to the image on the retina, now appear insignificant in comparison with the incongruities which we have met with in the field of sensation. One might almost believe that Nature had here contradicted herself on purpose, in order to destroy any dream of a pre-existing harmony between the outer and the inner world. "And what progress have we made in our task of explaining Sight? It might seem that we are farther off than ever; the riddle only more complicated, and less hope than ever of finding out the answer. The reader may perhaps feel inclined to reproach Science with only knowing how to break up with fruitless criticism the fair world presented to us by our senses, in order to annihilate the fragments." (p. 269.) How triumphant does Idealism now appear! How little trustworthy that boasted sense of which mankind have constantly said, "seeing is believing," although an apostle and philosophers innumerable have put the two in opposition!