Life can only be understood backwards; but it must be lived forwards.

The line is attributed to Søren Kierkegaard in his journals from the early 1840s, a period when he was developing his distinctive “existential” critique of speculative philosophy and reflecting on the tension between lived experience and retrospective understanding. Kierkegaard repeatedly contrasts the immediacy of life—choice, risk, and commitment in time—with the way meaning becomes visible only after events have unfolded. The remark fits his broader preoccupation with inwardness and the individual’s task of becoming a self, especially against systems (notably Hegelianism) that claim to comprehend life as a completed rational whole.

Kierkegaard points to a basic asymmetry: we make decisions without full knowledge, yet we interpret those decisions only later, when consequences and patterns emerge. “Understood backwards” suggests that coherence, causality, and meaning are largely retrospective constructions; we narrate our lives from outcomes to origins. But “lived forwards” insists that existence is not a solved problem: it is enacted in uncertainty, where faith, responsibility, and choice cannot be replaced by detached explanation. The saying captures Kierkegaard’s view that reflection is indispensable but never substitutes for living—understanding follows life, while life demands action before understanding is complete.

“Life can only be understood backwards, but it must be lived forwards.”
“Life can only be understood backwards; but it must be lived forward.”
“Life can only be understood backwards; but it must be lived forwards.”