Why are men, who need each other so much, always in opposition? This introduction to Rousseau''s thought, based on his four major works: Discours sur les sciences et les arts, Discours sur l''inégalité, Du Contrat social and l''Émile, helps us understand how this man who went against the grain of his time was a precursor. Rousseau was one of the few thinkers of his time to denounce the idea of progress as the source of human corruption. For him, it was a matter of rethinking and changing political society, with the aim of human emancipation from all powers.