The philosophy of history may be said to comprise three interrelated domains: historicity (Geschichtlichkeit), historiography (Historie), and history proper (Geschichte. A brief preliminary definition of each of these three concepts will guide the discussion into the three main divisions of the present chapter, (i) Historicity is the fundamental structure constitutive of the being of man and grounded in temporal being-in-the-world. Temporality is understood as the temporalizing unity of past, present, and future. Grounded in temporalizing, historicity is the domain of the phenomenology of historical existence, (ii) Historiography may be defined as the discipline and science of the writing of history; in short, the work and methods of historians of all sorts. Historiography must be rooted in a general concept of science which presupposes and is possible only for an historical being such as man. (iii) History most properly speaking is the eventuation of those most basic epochs in which Being is necessarily revealed and/or concealed. Heidegger calls history in this sense Seinsgeschichte or Being-as-History.