It is sometimes assumed that memory came of age in the wake of Rousseau, throwing off the fetters of eighteenth-century rationalism and asserting itself as a source of personality and individuality rather than the handmaiden of factual truth and objective knowledge. The nineteenth century, it has recently been suggested, should therefore be called the century of memory. 1 But this view implies a misunderstanding of eighteenth-century developments. Both Diderot and Rousseau, in different ways, had dissented from the rationalism of their times, deploring its narrow concern with ‘scientific’ knowledge at the expense of inner conviction. Rousseau championed sensibility and the rule of the heart, and throughout his writings Diderot argued the claims of independent thought and the autonomous self: despite his attraction to the philosophy of materialism, he was always drawn by the force of what could not be physically accounted for or rationally deduced.