From
朱熹《
观书有感·
其一》 (Zhu Xi, Southern Song, 12th c.), a 28-character philosophical quatrain:
半亩方塘一鉴开,
天光云影共徘徊。
问渠那得清如许?
为有源头活水来 (A half-mu square pond opens like a mirror; sky-light and cloud-shadow linger together. Ask that channel — how can it be so clear? Because a living spring feeds it at its source). Zhu Xi, the great Neo-Confucian synthesizer, uses the pond as an allegory for the mind kept pure by continuous inquiry.