Voltaire, Rousseau, Diderot--of the triumvirate that dominated French letters in the eighteenth century, Diderot was unmatched in the sheer breadth and depth of his interests and ideas. Rameau's Nephew and D'Alembert's Dream are dazzling expos s of Diderot's radical scientific and philosophical thinking. Written in dialogue form, they were too outspoken to be published during the lifetime of one whose ideas earned him enemies as fast...