But we must here observe that, beneficial as the intellectual reaction of this great crisis undoubtedly was, its effects could not be realized until the ardour of the revolutionary spirit had been to some extent weakened. The dazzling light thrown upon the Future for some time obscured our vision of the Past. It disclosed, though obscurely, the third term of the social progression; but it prevented us from fairly appreciating the second term. It encouraged that blind aversion to the Middle Ages, which had been inspired by the emancipating process of modern times; a feeling which had once been necessary to induce us to abandon the old system. The suppression of this intermediate step would be as fatal to the conception of Progress as the absence of the last; because this last differs too widely from the first to admit of any direct comparison with it. Right views upon the subject were impossible therefore until full justice had been rendered to the Middle Ages, which form at once the point of union and of separation between ancient and modern history. Now it was quite impossible to do this as long as the excitement of the first years of the revolution lasted. In this respect the philosophical reaction, organized at the beginning of our century by the great De Maistre, was of material assistance in preparing the true theory of Progress. His school was of brief duration, and it was no doubt animated by a retrograde spirit; but it will always be ranked among the necessary antecedents of the Positive system; although its works are now entirely superseded by the rise of the new philosophy, which in a more perfect form has embodied all their chief results. What was required therefore for the discovery of Sociological laws, and for the establishment upon these laws of a sound philosophical system, was an intellect in the vigour of youth, imbued with all the ardour of the revolutionary spirit, and yet spontaneously assimilating all that was valuable in the attempts of the retrograde school to appreciate the historical importance of the Middle Ages. In this way and in no other could the true spirit of history arise. For that spirit consists in the sense of human continuity, which had hitherto been felt by no one, not even by my illustrious and unfortunate predecessor Condorcet. Meantime the genius of Gall was completing the recent attempts to systematize biology, by commencing the study of the internal functions of the brain; as far at least as these could be understood from the phenomena of individual as distinct from social development. And now I have explained the series of social and intellectual conditions by which the discovery of sociological laws, and consequently the foundation of Positivism, was fixed for the precise date at which I began my philosophical career: that is to say, one generation after the progressive dictatorship of the Convention, and almost immediately after the fall of the retrograde tyranny of Bonaparte.