As a politician and intellectual, Benjamin Constant struggled to defend the Themidorean regime, which was tainted by immorality and illegitimacy. To achieve this goal, Constant synthesized and transformed the ideas of Montesquieu and Rousseau. His thoughts stemed from a mixture of liberalism that vindicated the interests of the bourgeoisie, and republicanism that embodied the ideas of liberal state. Both ideologies had been sanctified by the Revolution. In the process, he unintentionally developed the ground for the modern republican liberalism. He emphasized civil liberty and civil rights in modern society, and also respected political liberty through a representative system embodying the ‘general will’. He criticized the ‘liberty of ancients’ and the idea of popular sovereignty insisted by Rousseau. Instead he advocated the ‘liberty of moderns’. The core of Constant’s political thoughts lies not in people’s revolutionary ‘volition’ but in a representative ‘institution’ based on constitutionalism.