supererogation

This is one of those churchy words that sounds as if it should come with candles and a stern bishop. In Late Latin, superērogātiō was literally an added payment — super for “over,” ērogāre for “to pay out” — and then Christian writers gave it a moral glow: not just paying what you owe, but paying extra. That extra-ness mattered in medieval theology, where monks, nuns, and saints were imagined as stacking up surplus merit, a spiritual storehouse later tangled up with indulgences and the Reformation. The oddest little hinge is rogāre, “to ask,” a cousin of words like prerogative and abrogate, all circling around the idea of a formal request or decree. So supererogation is basically duty with a halo bolted on: not enough to meet the bill, but to leave a tip big enough for heaven to notice.