Life: Retrospective and Progressive

One of my favourite quotations is: Life must be understood backwards but it must be lived forwards. It originates from an 1843 entry in The Journals of Soren Kierkegaard. Here's what Kierkegaard originally said in context:

It is perfectly true, as philosophers say, that life must be understood backwards. But they forget the other proposition, that it must be lived forwards. And if one thinks over that proposition it becomes more and more evident that life can never really be understood in time simply because at no particular moment can I find the necessary resting-place from which to understand it backwards.