How is Rousseau's The Social Contract considered to be a gain changer in the history of political philosophy?

The Social Contract influenced governments throughout Europe and helped to promote political reform and revolution. Although Rousseau, for the most part, avoids discussion of contemporary political affairs, his criticism of luxury and his emphasis on popular sovereignty certainly contributed to the ideals of the French Revolution. In addition, many political leaders believed that Rousseau's political theories provided a solid foundation for any state. Rousseau was invited to draft constitutions for both Corsica and Poland, although his recommendations were never implemented because of foreign invasions.

The Social Contract is, in many ways, a follow-up to Discourse on the Origin and Basis of Inequality among Men. In the earlier work, Rousseau attacks private property for causing inequality and exploitation. These vices are responsible for the "chains" that Rousseau refers to in the first sentence of On the Social Contract. Accepting that some loss of liberty is inevitable, Rousseau seeks to establish a legitimate, political authority. The Social Contract thus examines what constitutes such an authority.