In the months following the end of World War I, French writer Henri Barbusse founded a group and a journal entitled Clarté with the aim of counteracting nationalist sentiment and building bridges between the peoples of Europe. Initially intrigued by the idea, both Stefan Zweig and Romain Rolland distanced themselves from Clarté, when the group adopted an increasingly uniform socialist outlook. This did not however prevent them from being drawn into a sometimes fierce debate about the social responsibility of the writer, initiated by Clarté. Drawing on the unpublished correspondence between Stefan Zweig and Henri Barbusse, this essay retraces the development of the Clarté controversy and examines, which ideological differences made collaboration between the three writers impossible.