From 《
论语·
子张》, the words of Confucius's disciple Zixia (
子夏):
仕而优则学,
学而优则仕 — 'When one serves with capacity to spare, one studies; when one studies with capacity to spare, one serves.'
优 here means 'having surplus / ease,' NOT 'excellent' — a common misreading. The saying structured Confucian scholar-official life for two millennia.