TECMESSA: Ignorant men
Don’t know what good they hold in their hands until
They’ve flung it away.

Sophocles (496-406 BC) Greek tragic playwright
Ajax, l. 964 [tr. Moore (1959)]

Alt trans.:
  • “Men of perverse opinion do not know / The excellence of what is in their hands, / Till some one dash it from them.” [George Young (1888)]
  • "Men of ill judgement oft ignore the good / That lies within their hands, till they have lost it."
  • "For those who are base in judgement do not know the good they hold in their hands until they cast it off."