This is one of the outstanding biographies of a philosopher. Wittgenstein's contribution to 20th-century philosophy is immense. Monk manages both to illuminate Wittgenstein's psychologically complex, yet outwardly austere life and to give a sense of the philosophical problems with which Wittgenstein was grappling. Review by Nigel Warburton, author of 'Philosophy: The Classics' (Kirkus UK)