In 1769 Diderot composed three dialogues, of which he said that, with a certain mathematical memoir, they were the only writings of his own with which he was contented. The first is a dialogue between himself and D'Alembert; the second is D'Alembert's Dream, in which D'Alembert in his sleep continues the discussion, while Mdlle. Lespinasse, who is watching by his bedside, takes down the dreamer's words; in the third, Mdlle. Lespinasse and the famous physician, Bordeu, conclude the matter.[213] It is impossible, Diderot said to Mdlle. Voland, to be more profound and more mad: it is at once a supreme extravagance, and the most deep-reaching philosophy. He congratulated himself on the cleverness of placing his ideas in the mouth of a man who dreams, on the ground that we must often give to wisdom the air of madness, in order to secure admittance. Mdlle. Lespinasse was not so complacent. She made D'Alembert insist that the dialogue should be destroyed, and Diderot believed that he had burned the only existing copy. As a matter of fact, the manuscript was not published until 1830, when all the people concerned had long been reduced to dust. There are five or six pages, Diderot said to Mdlle. Voland, which would make your sister's hair stand on end. A man may be much less squeamish than Mdlle. Voland's sister, and still pronounce the imaginative invention of D'Alembert's Dream, and the sequel, to be as odious as anything since the freaks of filthy Diogenes in his tub. Two remarks may be made on this strange production. First, Diderot never intended the dialogues for the public eye. He would have been as shocked as the Archbishop of Paris himself, if he had supposed that they would become accessible to everybody who knows how to read. Second, though they are in form the most ugly and disgusting piece in the literature of philosophy, they testify in their own way to Diderot's sincerity of interest in his subject. Science is essentially unsparing and unblushing, and D'Alembert's Dream plunged exactly into those parts of physiology which are least fit to be handled in literature. The attempt to give an air of polite comedy to functions and secretions must be pronounced detestable, in spite of the dialectical acuteness and force with which Diderot pressed his point. [213] _Oeuv._, ii.