Diderot, for all the robustness and penetration of his judgment, was yet often borne by his natural impetuosity towards the region of paradox.

His own curious and bold _Supplement au Voyage de Bougainville_ is entirely in the vein of Rousseau's discourse on the superiority of primitive over civilised life.

"Prodigious sibyl of the eighteenth century," cries Michelet, "the mighty magician Diderot! He breathed out one day a breath; lo, there sprang up a man--Rousseau."[87] It is hard to believe that such an astonishing genius for literature as Rousseau's could have lain concealed, after he had once inhaled the vivifying air of Paris.

Yet the fire and inspiring energy of Diderot may well have been the quickening accident that brought his genius into productive life.

All the testimony goes to show that it was so.