"War Diaries" is a collection of personal notebooks kept by the philosopher during the early years of World War II, specifically from 1939 to 1940. These diaries provide a unique insight into his thoughts and feelings during this tumultuous period, capturing his reflections on the intellectual and social climate of the time. The entries delve into his philosophical musings, everyday challenges, and his observations on the impact of the war on French society and culture. Through these diaries, readers gain an intimate understanding of the author's development of existential ideas in response to the war's unfolding events.