The energies of the _Philosophes_ were given a centre and a rallying-point by the great undertaking of the _Encyclopaedia_, the publication of which covered a period of thirty years (1751-80). The object of this colossal work, which contained a survey of human activity in all its branches--political, scientific, artistic, philosophical, commercial--was to record in a permanent and concentrated form the advance of civilization. A multitude of writers contributed to it, of varying merit and of various opinions, but all animated by the new belief in reason and humanity. The ponderous volumes are not great literature; their importance lies in the place which they fill in the progress of thought, and in their immense influence in the propagation of the new spirit. In spite of its bulk the book was extremely successful; edition after edition was printed; the desire to know and to think began to permeate through all the grades of society. Nor was it only in France that these effects were visible; the prestige of French literature and French manners carried the teaching of the _Philosophes_ all over Europe; great princes and ministers--Frederick in Prussia, Catherine in Russia, Pombal in Portugal--eagerly joined the swelling current; enlightenment was abroad in the world. The _Encyclopaedia_ would never have come into existence without the genius, the energy, and the enthusiasm of one man--DIDEROT. In him the spirit of the age found its most typical expression. He was indeed _the Philosophe_--more completely than all the rest universal, brilliant, inquisitive, sceptical, generous, hopeful, and humane. It was he who originated the _Encyclopaedia_, who, in company with Dalembert, undertook its editorship, and who, eventually alone, accomplished the herculean task of bringing the great production, in spite of obstacle after obstacle--in spite of government prohibitions, lack of funds, desertions, treacheries, and the mischances of thirty years--to a triumphant conclusion. This was the work of his life; and it was work which, by its very nature, could leave--except for that long row of neglected volumes--no lasting memorial. But the superabundant spirit of Diderot was not content with that: in the intervals of this stupendous labour, which would have exhausted to their last fibre the energies of a lesser man, he found time not only to pour out a constant flow of writing in a multitude of miscellaneous forms--in dramas, in art criticism, in philosophical essays, and in a voluminous correspondence--but also to create on the sly as it were, and without a thought of publication, two or three finished masterpieces which can never be forgotten. Of these, the most important is _Le Neveu de Rameau_, where Diderot's whole soul gushes out in one clear, strong, sparkling jet of incomparable prose. In the sheer enchantment of its vitality this wonderful little book has certainly never been surpassed.