This book, the text of Martin Heidegger's lecture course of 1929/30, is crucial for an understanding of Heidegger's transition from the major work of his early years, Being and Time, to his later preoccupations with language, truth, and history. First published in German in 1983 as volume 29/30 of Heidegger's collected works, The Fundamental Concepts of Metaphysics presents an extended treatment of the history of metaphysics and an elaboration of a philosophy of life and nature. Heidegger's concepts of organism, animal behavior, and environment are uniquely developed and defined with intensity. Of major interest is Heidegger's brilliant phenomenological description of the mood of boredom, which he describes as a "fundamental attunement" of modern times.