 However, there is some evidence of Hume intercepting even Rousseau's outgoing mail.After some correspondence with Rousseau, which included an eighteen-page letter from Rousseau describing the reasons for his resentment, Hume concluded that Rousseau was losing his mental balance.On learning that Rousseau had denounced him to his Parisian friends, Hume sent a copy of Rousseau's long letter to Madame de Boufflers.