No other philosopher has had as great an influence on 20th-century Anglo-American philosophy as Ludwig Wittgenstein. So says Walter Kaufmann in his preface to Bartley's illuminating study which alters the notion that Wittgeinstein abandoned philosophy between writing Tractatus Logico-Philosophicus, just after World War I, and the return to Cambridge to teach in 1929. Rather Wittgenstein was acting upon his own dictum that ""doing philosophy"" should produce moral change. The period during which he worked, then, in Austria -- as gardener, hotel porter, schoolteacher -- was the very active transition during which his final work Philosophical lnvestigations was written, a tour de force which appeared to completely and astonishingly reverse the initial Tractatus. Bartley limns the hitherto obscure ""dark decade,"" tracking down the Austrian influences of the time on the philosopher, ultimately providing a far less mysterious picture of the man and making the thinker more accessible on human and, most important, on theoretical grounds. An accessible study, but nowhere near as original and penetrating as Janik and Toulmin's brilliant book on the man and the zeitgeist, Wittgenstein's Henna (KR, 1972, p. 1283).