He was born in Nantes, Loire-Atlantique of a petit bourgeois family. He attended the Nantes Lycée, where, in 1877, he developed a close friendship with Jules Verne. He studied law, and soon went into politics, associating himself with the most advanced movements, writing articles for the Syndicalist journal Le Peuple, and directing the Lanterne for some time. From this he passed to the Petite République, leaving it to found L'Humanité, in collaboration with Jean Jaurès.