This study considers the work of Voltaire in the diversity of its forms and genres that the author has practiced. She first studied staging dialogued Voltaire discursive conflicts on the question of truth in the XVIIIth century. It then addresses the writer's ironic representation of voices claiming to assert authoritarian and dogmatic forms of truth-telling. Thirdly, it examines the writer's formal distinction between narrative fiction and historical narrative. Finally, the elements of writing that give Voltaire an existential need for truth are studied.--Éditions Vrin.