Rousseau is often seen as the quintessential representative of Swiss republicanism. But to most of his Swiss contemporaries Rousseau's brand of republicanism and his self-professed Protestantism remained deeply suspect. They found his thinking, and especially his discussion of the natural origins of morality, far too sceptical and thus ultimately unsuited for their own attempt to forge a theory of republican reform. The article focuses on the reply by Rousseau's most sympathetic yet also most persistent critics, the Basle secretary of state and author of the famous ‘History of Mankind’.