Martin Heidegger (September 26, 1889 – May 26, 1976) was a German philosopher. He studied at the University of Freiburg under Edmund Husserl, the founder of phenomenology, and became a professor there in 1928. He influenced many other major philosophers, and his own students at various times included Hans-Georg Gadamer, Hans Jonas, Emmanuel Levinas, Hannah Arendt, Leo Strauss, Xavier Zubiri and Karl Löwith. Maurice Merleau-Ponty, Jean-Paul Sartre, Jacques Derrida, Michel Foucault, Jean-Luc Nancy, and Philippe Lacoue-Labarthe also studied his work more or less closely. Beyond his relation to phenomenology, Heidegger is regarded as a major or indispensable influence on existentialism, deconstruction, hermeneutics and postmodernism. He attempted to reorient Western philosophy away from metaphysical and epistemological and toward ontological questions, that is, questions concerning the meaning of being, or what it means to be. He was also a prominent academic member of the Nazi Party.

The Concept of Time presents the reconstructed text of a lecture delivered by Martin Heidegger to the Marburg Theological Society in 1924. It offers a fascinating insight into the developmental years leading up to the publication, in 1927, of his magnum opus Being and Time, itself one of the most influential philosophical works this century.

In The Concept of Time Heidegger introduces many of the central themes of his analyses of human existence which were subsequently incorporated into Being and Time , themes such as Dasein, Being-in-the-world, everydayness, disposition, care, authenticity, death, uncanniness, temporality and historicity. Starting out by asking: What is time?, Heidegger proceeds to radicalise the concept of time and our relation to it, ending with the question: Are we ourselves time? Am I time?