One grain of sand is never a heap — so when does a heap begin?

Take a heap of sand and remove one grain: still a heap. Repeat that step a million times, one grain at a time, and logic says you should still call it a heap — even down to a single grain. The paradox, credited to the ancient logician Eubulides, exposes how ordinary words like 'heap', 'bald' and 'tall' have no exact threshold, yet we use them as if they did.

— Diogenes Laërtius, Lives of Eminent Philosophers — Book II, on Eubulides of Miletus — 3rd century AD, public domain