In Essays in Existentialism, Jean-Paul Sartre (1905-1980), the leading French exponent of existential philosophy, wrote a book that opened many doors to the mind. Sartre challenged his readers to think beyond the meaning of their everyday thoughts and beliefs. His essays on nothingness, on the emotions, and on the image - including "The Problem of Nothingness," "The Role of the Image in Mental Life," and "Essays in Aesthetics" - contain the essentials of his metaphysical speculations.