The philosophy of the eighteenth century opens the second period of the Cartesian era; it proposed to itself to apply the method already discovered and too much neglected,--it applied itself to the analysis of thought. Disabused of ambitious and sterile attempts, and, like Descartes, disdainful of the past, the eighteenth century dared to think that every thing in philosophy was to be done over again, and that, in order not to wander anew, it was necessary to set out with the modest study of man. Instead, therefore, of building up all at once systems risked upon the universality of things, it undertook to examine what man knows, what he can know; it brought back entire philosophy to the study of our faculties, as physics had just been brought back to the study of the properties of bodies,--which was giving to philosophy, if not its end, at least its true beginning. The great schools which divide the eighteenth century are the English and French school, the Scotch school, and the German school, that is to say, the school of Locke and Condillac, that of Reid, that of Kant. It is impossible to misconceive the common principle which animates them, the unity of their method. When one examines with impartiality the method of Locke, he sees that it consists in the analysis of thought; and it is thereby that Locke is a disciple, not of Bacon and Hobbes, but of our great countryman, Descartes.[8] To study the human understanding as it is in each one of us, to recognize its powers, and also its limits, is the problem which the English philosopher proposed to himself, and which he attempted to solve. I do not wish to judge here of the solution which he gave of this problem; I limit myself to indicating clearly what was for him the fundamental problem. Condillac, the French disciple of Locke, made himself everywhere the apostle of analysis; and analysis was also in him, or at least should have been, the study of thought. No philosopher, not even Spinoza, has wandered farther than Condillac[9] from the true experimental method, and has strayed farther on the route of abstractions, even verbal abstractions; but, strange enough, no one is severer than he against hypotheses, save that of the statue-man. The author of the _Traite des Sensations_ has very unfaithfully practised analysis; but he speaks of it without cessation. The Scotch school combats Locke and Condillac; it combats them, but with their own arms, with the same method which it pretends to apply better.[10] In Germany, Kant wishes to replace in light and honor the superior element of human consciousness, left in the shade, and decried by the philosophy of his times; and for that end, what does he do? He undertakes a profound examination of the faculty of knowing; the title of his principal work is, _Critique of Pure Reason_;[11] it is a critique, that is to say again, an analysis; the method of Kant is then no other than that of Locke and Reid. Follow it until it reaches the