Felix qui potuit rerum cognoscere causas.
Blessed is he who has been able to win knowledge of the causes of things.
Virgil, Georgics (29 BC), Book II, line 490 (tr. H. Rushton Fairclough); homage to Lucretius.
John Dryden’s translation:
Happy the man, who, studying nature’s laws,
Thro’ known effects can trace the secret cause.