This book offers a Wittgensteinian study of concept possession and of the nature of conceptual investigation in philosophy. It is both an ideal advanced introduction to Wittgenstein's philosophy and an original treatment of some of its most crucial yet least developed regions. The book is written as a Socratic dialogue, which frames the discussion within a backward glance to Plato's Theory of Forms. In so doing it makes a bold claim as to Wittgenstein's place in Western philosophy.