Human beings are essentially historical. They are born into an environment already formed by multiple layers of interpretation and tradition, even down to the most seemingly immediate sense of things and of the ‘I’ that perceives and thinks them. Heidegger’s summary statement that ‘The essence of Dasein lies in its existence’ (BT: 67) means that our lives do not express some pre-given, timeless human nature. We are, essentially, that nexus of practices, assumptions, prejudices, habits and traditions that make up the everyday experiences and actions in which we find ourselves: ‘One is what one does’ (BT: 283). But that ‘world’ in which we find our existence is not static: basic attitudes and assumptions alter. They alter in ways that cannot be calculated or predicted. This makes up Heidegger’s crucial notion, ‘the history of being’ (Seinsgeschichte). It can conveniently be expressed by the phrase ‘deep history’.