We have already seen how warm and close an intimacy subsisted between them in the days when Diderot was a prisoner at Vincennes (1749).

When Rousseau made up his mind to leave Paris and turn hermit (1756), there was a loud outcry from the social group at Holbach's.

They said to him, in the least theological dialect of their day, what Sir Walter Scott had said to Ballantyne when Ballantyne thought of leaving Edinburgh, that, "when our Saviour himself was to be led into temptation, the first thing the Devil thought of was to get him into the wilderness." Diderot remonstrated rather more loudly than Rousseau's other friends, but there was no breach, and even no coolness.

What sort of humours were bred by solitude in Rousseau's wayward mind we know, and the Confessions tell us how for a year and a half he was silently brooding over fancied slights and perhaps real pieces of heedlessness.

Grimm, who was Diderot's closest friend next to Mademoiselle Voland, despised Rousseau, and Rousseau detested Grimm.