I have already said, and, it seems to me, at sufficient length, how it is that progress does not exist as something imperative or regulative over the natural and immediate succession of the generations of men. That is as intuitive as is the actual coexistence of peoples, of nations and of states, which find themselves, at the same time, in a different stage of development; so undeniable is the actual condition of relative superiority and inferiority of nation as compared with nation; and again so certain is the partial and relative retrogression which has been produced several times in history, as Italy has exemplified for centuries. Still more, if there is a convincing proof of how progress must be understood in the sense of immediate law, and, to use a strong expression, of a physical and inevitable law, it is precisely this fact,--that social development by the very reasons of the _processus_ which are inherent in it, often leads to retrogression. It is evident, on the other hand, that the faculty of progressing, like the possibility of retrogressing, does not constitute, to begin with, an immediate privilege, or an innate defect of a race, nor is either one the direct consequence of geographical conditions. And, in fact, the primitive centers of civilization were multiple, those centers have been removed in the course of centuries, and finally the means, the discoveries, the results and the impulses of a definite civilization, already developed, are, within certain limits, communicable to all men indefinitely. In a word, progress and retrogression are inherent in the conditions and the rhythm of social development. Now then, the faith in the universality of progress, which appeared with so much violence in the eighteenth century, rests upon this first positive fact, that men, when they do not find obstacles in external conditions, or do not find them in those which result from their own work in their social environment, are all capable of progress.