In the first two Discourses, Rousseau focuses on the ideal of the noble savage, which seems more romantic in its way, but in the Second Discourse, Rousseau admits that to go back to that ancient period is impossible, given what we are like now. Instead, society must now be based on reason and equality and freedom. The Enlightenment emphasis is strongest in the Third Discourse, where Rousseau sets out his conditions for political legitimacy which rely largely on state coercion being used in and only within line with the general will or "public reason" of a society.
A Discourse on Inequality