Rameau’s Nephew submits to no simple classification. Although the narrative is fictional, the characters are actual persons and the ideas they expound in the book probably closely resemble the opinions they actually held. There is the problem of deciding how much of Denis Diderot can be found in the character Rameau, and how much of Rameau in that of Diderot. In general, however, the Diderot in the book is a mild champion of traditional values whereas Rameau is a vivacious apologist for roguery. The brilliant turns of this satirical dialogue raise the suspicion that the author Diderot is delighted with the convention-defying attitudes of his friend Rameau; perhaps Diderot believes Rameau more than Rameau believes himself.

The dialogue is a satirical critique of manners and morals. It makes specific reference to prominent writers, musicians, politicians, critics, and other leading figures of eighteenth century France. Many of the comments are unkind, and some are painfully so—or would have been had the work been published at the time of its composition. Diderot saw to it, however, that his lively satire remained unpublished, not only because of its references to living persons but also because of a reluctance to stir up the censor and all those to whom Rameau’s carefree morality might have proved unacceptable.

The character Rameau is marvelously wrought to suit Diderot’s intention. Although Rameau is a fully drawn individual and convincing, as witty rogues in literature usually are, he is not simply one thing or another. On the contrary, Diderot states that Rameau is simultaneously his own opposite. Sometimes Rameau is thin, sometimes fat; sometimes he is filthy, sometimes powdered and curled. His physical vacillation is matched by vacillations of mood. Sometimes he is cheerful, sometimes depressed; sometimes he is courageous, sometimes timid to the point of being fearful. Rameau is a sensualist and a lover of wine and women, but his passionate defense of an egoistic hedonism is a sign of his need to apologize for his manner: His morality is a device to prop up his manner. Underneath Rameau’s abandon can be perceived a poignant longing for depth and respectability.

Having created a character whose contrary traits reveal the human being in self-conflict—thus providing the motive for a discussion of morality—Diderot provides Rameau with a gentlemanly antagonist, the man of ideas, Diderot himself. Diderot’s mild responses, ostensibly intended to counter Rameau’s philosophy, actually, with the acuity of a Socrates, incite Rameau to a passionate defense of the sense-gratifying life of a social parasite.

Rameau, who contradicts himself within himself, and Diderot, who contradicts Rameau, together bring out the difficulty of all moral problems and of morality itself. Human beings are neither merely intellectual nor merely sensual; their desire to understand is often in conflict with their desires, and their desires in conflict with one another. Consequently, no one moral rule or set of principles will do. To be a good person, one must have a kind of moral genius. For such a person, rules are instruments to be used only with ingenuity, and sometimes they need to be discarded altogether. People who are at war with themselves, or with another, as Rameau is with himself and with Diderot, may not be able to attain a just victory. Sometimes there is no such thing as the proper answer. For a good person, life is a creative struggle that must be judged as works of art are judged, without dogmatism and with respect for the impossible goals the human spirit sets for itself. Perhaps the theme of the dialogue is best understood dialectically: Without the restraint of reason and human...