We have already, in discussing Voltaire, adverted sufficiently to Mr. John Morley's volumes in honor of Diderot and his compeers. Diderot is therein ably presented in the best possible light to the reader; and we are bound to say that, despite Mr. Morley's friendly endeavors, Diderot therein appears very ill. He married a young woman whose simple and touching self-sacrifice on her husband's behalf he presently requited by giving himself away, body and soul, to a rival. In his writings he is so easily insincere that not unfrequently it is a problem, even for his biographer, to decide when he is expressing his sentiments truly and when not, insomuch that, once and again, Mr. Morley himself is obliged to say, "This is probably hypocritical on Diderot's part," or something to that effect. As for filthy communication out of his mouth and from his pen--not, of course, habitual, but occasional--the subject will not bear more than this mention. These be thy gods, O Atheism! one, in reading Mr. Morley on Diderot, is tempted again and again to exclaim. To offset such lowness of character in the man it must in justice be added that Diderot was, notwithstanding, of a generous, uncalculating turn of mind, not grudging, especially in intellectual relations, to give of his best to others, expecting nothing again. Diderot, too, as well as Voltaire, had his royal or imperial friends, in the notorious Empress Catherine of Russia, and in King Stanislaus of Poland. He visited Catherine once in her capital, and was there munificently entertained by her. She was regally pleased to humor this gentleman of France, permitting him to bring down his fist in gesture violently on the redoubtable royal knee, according to a pleasant way Diderot had of emphasizing a point in familiar conversation. His truest claim to praise for intellectual superiority is, perhaps, that he was a prolific begetter of wit in other men.