It all yields nothing to modern science; the unwearying research is all carried on, as it were, in the dark; and the sleepless brain of the pioneer can but weave webs of impermanent speculation from masses of unsifted and unmanageable material. Powers which to-day, on a prepared ground of ascertained science, might yield the greatest results, were wasted in a gigantic effort to build a social science out of the chaos of undeciphered antiquity, natural and human. But the man is nonetheless morally memorable. Diderot pictures him with a head Socratically ugly, simple and innocent of life, gentle though vivacious, reading Rabbinical Hebrew in his walks on the high roads, suffering all his life from "domestic persecution," "little contradictory though infinitely learned," and capable of passing in a moment, on the stimulus of a new idea, into a state of profound and entranced absorption. Diderot is always enthusiastically generous in praise; but in reading and reviewing Boulanger's work we can hardly refuse assent to his friend's claim that "if ever man has shown in his career the true characters of genius, it was he." His immense research was all compassed in a life of thirty-seven years, occupied throughout in an active profession; and the diction in which he sets forth his imaginative construction of the past reveals a constant intensity of thought rarely combined with scholarly knowledge. But it was an age of concentrated energy, carrying in its womb the Revolution. The perusal of Boulanger is a sufficient safeguard against the long-cherished hallucination that the French freethinking of his age was but a sparkle of raillery.