It is widely acknowledged that the most powerful influence upon the contemporary practice of philosophy has been that of Ludwig Wittgenstein, who died at Cambridge in 1951. Wittgenstein avoided publicity; little has hitherto been known of his life and character outside the small circle of his relatives and friends. One of those friends, Professor Norman Malcolm of Cornell University, has now written a remarkably vivid personal memoir of this gifted, difficult man. As a frank portrait of a tormented genius, based on many unpublished letters, it will prove of absorbing interest not only to philosophers and students of philosophy but to all, at whatever remove, who have felt the impact of his thought. The memoir is supplemented by a biographical sketch by another of Wittgenstein's friends, Professor Georg Henrik von Wright of the University of Helsingfors.