During the phoney war that preceded the invasion of France, between late 1939 and the summer of 1940, the young Jean-Paul Sartre was stationed in his native Alsace as part of a meteorological unit. He used his considerable periods of spare time, between mundane duties like watching weather balloons, to make a series of notes on philosophy, literature, politics and autobiography that anticipate the themes of his later masterpieces, and often surpass them in literary verve and directness. These War Diaries form a portrait of Sartre in his most intense and brilliant phase. With them the twentieth century's most remarkable and public philosopher has provided us with a fitting posthumous monument to his honesty and creativity.