Heidegger presented this public address on 25 July 1924, to the Marburg Theologians Society. It contains the core structure of Being and Time. The central topic of the lecture is the question, What is time? Heidegger analyzes first the everyday concept of time. Time is related to movement. Aristotle and Albert Einstein agree that time exists only because of the events that happen within it. In natural science, time is measured by a now that is so much later than an earlier now and so much earlier than a later now. Yet, as Augustine has shown, we can measure time only through our disposedness. Time is clearly related to the being-there of human beings.
The way of being of being-there is determined by its particular whileness. The life of a human being is a succession of the particular whiles of its situation, and is extended between its birth and death. Being-there is primarily a being possible or can-be. Death is the undetermined certainty of being-there’s most unique possibility of being at an end. When being-there anticipates the certain possibility of its ceasing to be, it is with itself individually and truly existent. It thus becomes visible in its unique here-and-now and the once-and-for-all of its unique fate in the possibility of its one-and-only givenness. Being-there is its present in everydayness, its future in anticipation, and its past in historicality. Being-there is time, and therefore the most proper determination of time is that time is temporal. Heidegger rephrases the opening question of his lecture, “what is time?” as “who is time?” Are we ourselves time, or am I my time? If I were my time, being-there would become a question for itself. With this statement, Heidegger ends his lecture on the threshold of Being and Time.