From the Analects (《
论语·
子张》), spoken by Confucius's disciple Zixia (
子夏):
仕而优则学,
学而优则仕 — 'One who serves well should then study; one who studies well should then serve.'
优 here means 'to have spare capacity / to do well,' not just 'excellent.' This ideal shaped the imperial examination system (
科举) for over a thousand years.