Why do Helvetius's writings matter? Rousseau's Notes sur De l'esprit

De l'esprit was read and commented on by Rousseau, Diderot, and Voltaire, in 1758. So was De l'homme when it appeared posthumously in 1773. We will go into this series of books, marginalia, and refutations, to address the question: what exactly was widely discussed between the three authors during the 1750s? Is it materialism'? Our first point is to interpret the potential distortions, re-workings or re-appropriations in Rousseau's marginalia, known as Notes sur De l'esprit, especially here about the so-called theory of passive judgement. We will then see that there certainly is, in the discussion between Rousseau and Helvetius, a real opposition on the question of matter and its properties, as the examination of the Favre manuscript and the revised version of Emile would easily prove it. But this question is not the key to Rousseau's first reaction to Helvetius's De l'esprit. I shall focus on the moral and anthropological dimensions of the discussion in the Notes. From this point of view, we will suggest that the experience of real friendship has been part of the refutation of Helvetius by both Rousseau and Diderot, even long after their former very close friendship had been so definitely broken.