Locke's theory as probed and searched by Leibnitz. And in this uneasy state--half sceptical, half creative, rejecting and substituting, pulling down and building up--what was, in sum and finally, the course which he took for bringing his trials and essays to a crisis? He states this himself, somewhere in the Introduction to his _Critik der reinen Vernunft_; and the passage is a memorable one. Fifteen years at the least have passed since I read it; and, therefore, I cannot pretend to produce the words; but the substance I shall give; and I appeal to the candour of all his readers whether they have been able to apprehend his meaning. I certainly did not for years. But, now that I do, the passage places his procedure in a most striking and edifying light. Astronomers, says Kant, had gone on for ages, assuming that the earth was the central body of our system; and insuperable were the difficulties which attended that assumption. At length, it occurred to try what would result from inverting the assumption. Let the earth, instead of offering a fixed centre for the revolving motions of other heavenly bodies, be supposed itself to revolve about some one of these, as the sun. That supposition was tried, and gradually all the phenomena which, before, had been incoherent, anomalous, or contradictory, began to express themselves as parts of a most harmonious system. "Something," he goes on to say, "analogous to this I have practised with regard to the subject of my inquiry--the human understanding. All others had sought their central principle of the intellectual phenomena out of the understanding, in something external to the mind. I first turned my inquiries upon the mind itself. I first applied my examination to the very analysis of the understanding." In words not precisely these, but pretty nearly equivalent to them, does Kant state, by contradistinction, the value and the nature of his own procedure. He first, according to his own representation, thought of applying his investigation to the mind itself. Here was a passage which for years (I may say) continued to stagger and confound me. What! he, Kant, in the latter end of the 18th century, about the year 1787--he the first who had investigated the mind! This was not arrogance so much as it was insanity. Had he said--I, first, upon just principles, or with a fortunate result, investigated the human understanding, he would have said no more than every fresh theorist is bound to suppose, as his preliminary apology for claiming the attention of a busy world. Indeed, if a writer, on any part of knowledge, does _not_ hold himself superior to all his predecessors, we are entitled to say--Then, why do you presume to trouble us? It may _look_ like modesty, but _is_, in effect, downright effrontery, for you to think yourself no better than other critics; you were at liberty to think so whilst no claimant of public notice--as being so, it is most arrogant in you to be modest.