History as a discipline is not simply the study of or recounting of past events. It can only exist in cultures which have a historic sense, i.e. a realization that things have not always been as they are now and that the present is the product of a long process of change and development. Awareness of change through time in institutions, beliefs, and lifestyles is necessary for history as a discipline to exist. Otherwise there can only be chronicle and antiquarianism. In medieval Europe this historical sense did not exist, so that authors, with no sense of anachronism, could portray Troy as a typical medieval town and the heroes of the Trojan War as knights errant. History has an important part to play in all modern political philosophies as one of its main purposes is to explain how the present came to emerge from the past. It is therefore essential to any account of the nature of the present which would be comprehensive and complete that it contain an element of historical analysis. For some political philosophies, including, notably, Marxism, an account of history is the core of the entire philosophy.