Georg Henrik von Wright’s Wittgenstein is a reference book for Wittgenstein’s scholars. Three of the essays collected here provide necessary biographical information ("The Wittgenstein Papers", "The Origin of the Tractatus", "The Origin and Composition of the Philosophical Investigations"). Three others try to determine Wittgenstein’s position on difficult topics : probability, modalities and certainty. The last one gives an illuminating presentation of the conflictual relationship between Wittgenstein and his time.