The final wisdom of life requires not the annulment of incongruity but the achievement of serenity within and above it.

In this sentence Niebuhr frames maturity not as solving life’s contradictions but as learning to live faithfully amid them. “Incongruity” suggests the persistent mismatch between ideals and realities—between what we hope for (justice, coherence, moral purity) and what history and human nature actually deliver. The “final wisdom” is therefore a spiritual and ethical poise: serenity that neither denies conflict nor is crushed by it. The line resonates with Niebuhr’s broader Christian realism, which distrusts utopian confidence and emphasizes humility, repentance, and responsible action under conditions of ambiguity. Serenity here is not passivity but steadiness—an inner freedom that enables moral engagement without illusion.