This volume presents, for the first time in English, Husserl's seminal 1923/24 lecture course First Philosophy (Erste Philosophie) together with a selection of material from the famous research manuscripts of the same time period. The lecture course is divided into two systematic, yet interrelated parts ("Critical History of Ideas" and "Theory of the Phenomenological Reduction"). It has long been recognized by scholars as among the most important of the many lecture courses he taught in his career. Indeed it was deemed as crucially important by Husserl himself, who composed it with a view...