Jacques Pierre Brissot was highly influenced by the ethical principles theorized by philosopher Jean-Jacques Rousseau. Rousseau had wrote a book called The Social Contract that he theorized was the best way to establish a political community around the problems of commercial society. The Social Contract became very popular as it inspired many politicians and revolutions (like Brissot and the Jacobins) in not only France, but also throughout Europe.

Here’s a link to Rousseau’s Social Contract:
http://chnm.gmu.edu/revolution/d/275/