On Heidegger's Being and Time is an outstanding exploration and elucidation of Heidegger's most important work by two major philosophers, providing a master class in reading a philosophical classic. Simon Critchley begins by arguing that we must see Being and Time as a radicalization of Husserl's phenomenology, particularly his theories of intentionality, categorical intuition and the phenomenological concept of the a priori. Consequently, we must look at Heidegger's early work, reading him 'forward', if we are to make sense of the most important question Heidegger set himself: the question of Being. In contrast, Schurmann urges us to read Heidegger 'backward', arguing that his later work is the key to unravelling Being and Time.Through a close and compelling reading of the first eight sections of Being and Time Schurmann sets out three trajectories that shape the path of Heidegger's thinking: a transcendental analytic of Dasein, which demonstrates that Dasein's being is time; a fundamental ontology, which leads to an understanding of Being as time; and a historical destruction of the history of ontology which allows us to retrieve the question of Being through history or tradition. This is the first time that Schurmann's renowned lectures on Heidegger have been published. Schurmann and Critchley also explore and debate further key themes in Heidegger's work, including authenticity, his retrieval of the notion of 'wonder', and the vexed issue of the relationship between Heidegger's philosophy and his politics. With a helpful introduction by Steven Levine placing Schurmann and Critchley's arguments in context, On Heidegger's Being and Time is essential reading for anyone interested in Heidegger, phenomenology and one of the most important philosophical works of the twentieth century.