Voltaire and Rousseau are the two main intellectual creators of modern Europe. They both attacked feudalism. They complement each other, the one emphasizing reason and the other emotion.
Voltaire attacked superstitions and religous bigotry ( see Voltaire's ''Çandide'and 'Zadig'). Rousseau attacked the entire feudal system (see Rousseau's 'The Social Contract' and the 'Discourse on Inequality'). While Voltaire said that we should rely on reason and science instead of superstitions and dogma, Rousseau said that reason without passion (to fight against injustice) was sterile.