Would you learn the secret of the sea? / Only those who brave its dangers, / comprehend its mystery!
Verified
insightseaoceanmysterysecretunderstandingSource: 'The Secret of the Sea,' Henry Wadsworth Longfellow, in The Seaside and the Fireside, 1850
Genuine Longfellow, from the poem 'The Secret of the Sea.' The stanza is spoken in dialogue and the original is archaic: 'Wouldst thou' — so the helmsman answered — 'learn the secret of the sea? / Only those who brave its dangers / Comprehend its mystery!' The corpus text modernizes the opening and drops the helmsman frame. Poem attribution is certain; I am slightly less sure of the collecting volume, though The Seaside and the Fireside (1850) is my recollection.