The inroads of sensibility into French literature, as exemplified in Marivaux and Prévost in the thirties, followed swiftly by the rank and file, also wrought havoc in the old classical method, though this fact may not without further reflection be conceded. But in the broad realm of psychological observation, where classic art had reigned supreme, the influx of a certain morbid sensibility strangely warped the mental vision of the observer. Diderot, a veritable sinner himself in this respect, admits as much in an unguarded moment: "L'homme sensible est trop abandonné à la merci de son diaphragme ... pour être un profond observateur et conséquemment un sublime imitateur de la nature." Every one knows Voltaire's naïve statement which bears condemnatory evidence to the bluntness of his psychology. "La nature est partout la même." And is it not, we ask, this enigmatical typical man, out of space and out of time, for whom the chimerical theories of universal perfectibility were soon to be woven? It is incontestably true, then, that the character of human observation undergoes a sensible alteration in the course of the century, and that whereas the individual man had been heretofore studied inasmuch as he was in himself of typical value, henceforward not man the individual will be the object of study, but the observation of human relations will usurp the field, and psychological analysis will yield to social investigation. I would add a word or two by way of conclusion to illustrate how the encyclopedists in their propaganda, aided in part by the coincident influence of Rousseau, established ideals of thought and conduct which were in the most violent contrast to the ideals cherished in the preceding century. Of course, we readily understand that the encyclopedists threw to the four corners of heaven the outworn respect of religious and political tradition. Furthermore, we may ask ourselves what it is which in a sense makes Molière and La Fontaine isolated in their century; and the answer will not be far to seek when we realize that these two alone of all their fellows urged the suspected authority of instinct as a sufficient guide for conduct. Yet how far were not even these bolder spirits from the natural man of Rousseau or of Diderot?