"’Man alone is credited with being an exception to this rule. He is inferior in keenness of sense to the animals below him, yet superior in power. It is also noticeable that the savage is in like manner superior to the civilized man. It is therefore probable that man is really the possessor of a sixth sense as yet imperfectly developed and unequally distributed.’ "Briefly this is the key to the remarkable conclusions at which he eventually arrives, and which are worked out with his usual mathematical exactitude and care. He has fully satisfied me that this theory explains most of the mysteries of life; but there is not time now to go more fully into the matter." "But," I said, "he appears to have forgotten entirely the importance of intellect." "There you are mistaken. He goes very fully into the matter and anticipates Darwin. ’Intellect,’ he writes, ’is not a means of perception, but an organ for the arrangement and use of the senses, and is to be found in all animal life though in a less developed form than is noticeable in man.’" "But," I interrupted, "is not that therefore the explanation; the higher intellect of man needs a lower standard of sensitive faculty, and he is thus enabled to produce from lesser gifts a greater gain?" "I will," he answered, "as nearly as possible give you Descartes’ answer to this objection. ’To say that the more highly developed a being, the less it will require its perceptive powers, and that therefore through want of use they have gradually deteriorated, would lead us to this _reductio ad absurdum:_--that in time man will become so perfectly developed that his senses must continue deteriorating until at last he will arrive at the perfection of an insensitive existence, with intellect to place in order all things which he perceives while he is unable to perceive anything.’ Of course in endeavouring to give you his argument in a few words--an argument which requires close and careful reasoning, I do Descartes considerable injustice, but I hope on some future occasion to be able to go more fully into the discussion. I have said enough for my present purpose, and am not fond of argument unless satisfied that my opponent agrees with me upon the primary ground of discussion; much valuable time is otherwise wasted. For instance, if you are speaking on the subject of the colour red to a man born blind and his idea of red is some sound which resembles the blast of a trumpet, you cannot possibly hope to arrive at any very satisfactory conclusion. In the same way if man is unconscious of the power granted him through the sixth; or, as for lack of a better term we may call it, the spiritual sense, no argument on the subject would be of the least value. It will suffice at present to say that the theory which Descartes fully works out was to me personally a revelation; a revelation, because it seemed but the perfected expression of my own dormant thought.