It was Turgot, however, who completed the historical conception of Montesquieu, in a piece written in 1750, two years after the appearance of the _Esprit des Lois_, and in one or two other fragmentary compositions of about the same time, which are not the less remarkable because the writer was only twenty-three years old when these advanced ideas presented themselves to his intelligence. Vico in Italy had insisted on the doctrine that the course of human affairs is in a cycle, and that they move in a constant and self-repeating orbit.[49] Turgot, on the contrary, with more wisdom, at the opening of his subject is careful to distinguish the ever-varying spectacle of the succession of men from generation to generation, from the circle of identical revolutions in which the phenomena of nature are enclosed. In the one case time only restores at each instant the image of what it has just caused to disappear; in the other, the reason and the passions are ever incessantly producing new events. 'All the ages are linked together by a succession of causes and effects which bind the state of the world to all the states that have gone before. The multiplied signs of speech and writing, in supplying men with the means of an assured possession of their thoughts and of communicating them to one another, have formed a common treasure that one generation transmits to another, as an inheritance constantly augmented by the discoveries of each generation; and the human race, looked at from its origin, appears in the eyes of the philosopher one immense whole, which, just as in the case of each individual, has its infancy and its growth.'[50]
Pascal and others in ancient and modern times[51] had compared in casual and unfruitful remarks the history of the race to the history of the individual, but Turgot was able in some sort to see the full meaning and extent of the analogy, as well as the limitations proper to it, and to draw from it some of the larger principles which the idea involved. The first proposition in the passage just quoted, that a chain of causes and effects unites each age with every other age that has gone before, is one of the most memorable sentences in the history of thought. And Turgot not only saw that there is a relation of cause and effect between successive states of society; he had glimpses into some of the conditions of that relation. To a generation that stands on loftier heights his attempts seem rudimentary and strangely simple, but it was these attempts which cut the steps for our ascent. How is it, he asked, for instance, that the succession of social states is not uniform? that they follow with unequal step along the track marked out for them? He found the answer in the inequality of natural advantages, and he was able to discern the necessity of including in these advantages the presence, apparently accidental, in some communities and not in others of men of especial genius or capacity in some important direction.[52] Again, he saw that just as in one way natural advantages accelerate the progress of a society, in another natural obstacles also accelerate it, by stimulating men to the efforts necessary to overcome them: _le besoin perfectionne l'instrument_.[53] The importance of following the march of the human mind over all the grooves along which it travels to further knowledge, was fully present to him, and he dwells repeatedly on the constant play going on between discoveries in one science and those in another. In no writer is there a fuller and more distinct sense of the essential unity and integrity of the history of mankind, nor of the multitude of the mansions into which this vast house is divided, and the many keys which he must possess that would open and enter in.