Full Idea
Dasein is always only that which it has chosen to be.
Clarification
'Dasein' roughly means 'existence' or 'being there'
Gist of Idea
Dasein is always only that which it has chosen to be
Source
Martin Heidegger (Basic Problems of Phenomenology [1927], p.278), quoted by Richard Polt - Heidegger: an introduction 3.§39-42
Book Reference
Polt,Richard: 'Heidegger: an introduction' [Routledge 2003], p.78
A Reaction
I take it as significant that this is what it 'has' chosen, and not what it now 'chooses'. I might accept that my mode of existence results from past choices, but certainly not that I can choose it now. Ossified brain.