Who does not perceive that Luther, Descartes, and Voltaire employed the same method, and that they differed only in the greater or less use which they professed should be made of it? Why did the Reformers confine themselves so closely within the circle of religious ideas? Why did Descartes, choosing only to apply his method to certain matters, though he had made it fit to be applied to all, declare that men might judge for themselves in matters philosophical but not in matters political? How happened it that in the eighteenth century those general applications were all at once drawn from this same method, which Descartes and his predecessors had either not perceived or had rejected? To what, lastly, is the fact to be attributed, that at this period the method we are speaking of suddenly emerged from the schools, to penetrate into society and become the common standard of intelligence; and that, after it had become popular among the French, it has been ostensibly adopted or secretly followed by all the nations of Europe? The philosophical method here designated may have been engendered in the sixteenth century--it may have been more accurately defined and more extensively applied in the seventeenth; but neither in the one nor in the other could it be commonly adopted. Political laws, the condition of society, and the habits of mind which are derived from these causes, were as yet opposed to it. It was discovered at a time when men were beginning to equalize and assimilate their conditions. It could only be generally followed in ages when those conditions had at length become nearly equal, and men nearly alike. The philosophical method of the eighteenth century is then not only French, but it is democratic; and this explains why it was so readily admitted throughout Europe, where it has contributed so powerfully to change the face of society. It is not because the French have changed their former opinions, and altered their former manners, that they have convulsed the world; but because they were the first to generalize and bring to light a philosophical method, by the assistance of which it became easy to attack all that was old, and to open a path to all that was new.