With the unusual clarity, distinctive and engaging style, and penetrating insight that have drawn such a wide range of readers to his work, Ian Hacking here offers his reflections on the philosophical uses of history. The focus of this volume, which collects both recent and now-classic essays, is the historical emergence of concepts and objects, through new uses of words and sentences in specific settings, and new patterns or styles of reasoning within those sentences. In its lucid and thoroughgoing look at the historical dimension of concepts, the book is at once a systematic formulation of Hacking's approach and its relation to other types of intellectual history, and a valuable contribution to philosophical understanding.