We have lingered for a long time over the study of Saint-Simonianism. The reason is that aside from the fact that there are few doctrines richer in fertile observations, the school in certain respects has a very immediate interest. Its study is valuable for a better comprehension of the circumstances we find ourselves in today. In fact there are striking analogies between the period we have just been studying and the one in which we now live. From an intellectual point of view what characterizes the former is that the three following ideas were simultaneously produced: the idea of extending to social sciences the method of the positive sciences (out of which sociology has come) and the historical method (an indispensable auxiliary of sociology); 2. The idea of a religious regeneration; and, 3. The socialist idea. There is no question that in about ten years [written in 1896], we have seen these three currents reform themselves simultaneously and assume more and more intensity. The sociological idea, which had been neglected to the point that the word itself was unrecog nized, once more spread with extreme rapidity; a neo-religious school was founded and, however vague its concepts, one cannot deny that it is gaining more ground than it is losing; and the progress made in these last years by socialist thought is wellknown. When these three currents are viewed from the outside they seem to repel one another, and those most actively involved only see antagonism among them. The religious movement is presented as a protest against the ambitions of practical science; the socialist movement-because it carries with it a more or less definite solution of the social problems that concern us-cannot accept sociology unless it becomes subordinate and renounces itself, that is, as an independent science. It would therefore seem that there is only contradiction and opposition in these different tendencies of contemporary thought. Here the retrospective study we just made becomes instructive.