Never were ideas abused in so inhuman a fashion as between the close of the eighteenth century and the beginning of the nineteenth. The lesson of things was very hard, the saddest disillusions arose and a radical upheaval followed in the minds of men. Facts, in a word, proved to be contrary to all expectations; and this at first produced a profound discouragement among the disillusioned, which, notwithstanding, gave rise to the desire and the need of new investigations. We know that Saint Simon and Fourier, in whom operated precisely at the beginning of the century, in the exclusive forms of the ideas of premature genius, the reaction against the immediate results of the politico-economic revolution, arose resolutely, the first against the jurists, and the second against the economists. In fact, when once the obstacles to liberty, which had been characteristic of other times, had been suppressed, new obstacles, graver and more painful, had replaced them, and, as equal happiness for all was not realized, society remained in its political form as it had been before, an organization of inequalities. It must be, then, that society is something autonomous, innate, a complex automaton of relations and conditions, which defies the subjective good intentions of each of the members who compose it, and which escapes from the illusions and the designs of the idealists. It thus follows a course of its own from which we may infer certain laws of process and development, but does not suffer us to impose laws upon it. By this transformation in the minds of men, the nineteenth century heralded itself as the century of historic science and of sociology. The principle of development has, indeed, since then, invaded all domains of thought. In this century, the grammar of history has been discovered, and thus the key has been found to explore the genesis of myths. The embryonic traces of pre-history have been sought out, and, for the first time, the processes of political and legal forms have been arranged into a series. The nineteenth century heralded itself as the century of sociology in the person of Saint Simon, in whom, as happens with the self-taught precursors of genius, we find confused together the germs of so many contradictory tendencies. In this aspect the materialistic conception is a result; but it is a result which is the complement of the whole process of formation; and as a result and a complement it is also the simplification of all historic science and of all sociology, because it takes us back from things derived and from complex conditions to elemental functions. And that is brought about by the direct suggestion of new dynamic experience.