The philosophical views current in Germany during the period in which the psychology of Locke was in fashion in France and before the genius of Kant opened a new path, were based on the system of Leibnitz. We might therefore expect to find a theory of Progress developed there, parallel to the development in France though resting on different principles. For Leibnitz, as we saw, provided in his cosmic optimism a basis for the doctrine of human Progress, and he had himself incidentally pointed to it. This development, however, was delayed. It was only towards the close of the period--which is commonly known as the age of "Illumination"--that Progress came to the front, and it is interesting to observe the reason. Wolf was the leading successor and interpreter of Leibnitz. He constrained that thinker's ideas into a compact logical system which swayed Germany till Kant swept it away. In such cases it usually happens that some striking doctrines and tendencies of the master are accentuated and enforced, while others are suffered to drop out of sight. So it was here. In the Wolfian system, Leibnitz's conception of development was suffered to drop out of sight, and the dynamic element which animated his speculation disappeared. In particular, he had laid down that the sum of motive forces in the physical world is constant. His disciples proceeded to the inference that the sum of morality in the ethical world is constant. This dogma obviously eliminates the possibility of ethical improvement for collective humanity. And so we find Mendelssohn, who was the popular exponent of Wolf's philosophy, declaring that "progress is only for the individual; but that the whole of humanity here below in the course of time shall always progress and perfect itself seems to me not to have been the purpose of Providence." [Footnote: See Bock, Jakob Wegelin als Geschichtstheoretiker, in Leipsiger Studien, ix. 4, pp. 23-7 (1902).] The publication of the Nouveaux Essais in 1765 induced some thinkers to turn from the dry bones of Wolf to the spirit of Leibnitz himself. And at the same time French thought was penetrating. In consequence of these influences the final phase of the German "Illumination" is marked by the appearance of two or three works in which Progress is a predominating idea. We see this reaction against Wolf and his static school in a little work published by Herder in 1774--"a philosophy of history for the cultivation of mankind." There is continuous development, he declares, and one people builds upon the work of another. We must judge past ages, not by the present, but relatively to their own particular conditions. What exists now was never possible before, for everything that man accomplishes is conditioned by time, climate, and circumstances.