From Wei Zheng's (
魏征) Tang memorial 《
谏太宗十思疏》 (Ten Reflections Presented to Emperor Taizong), 637 CE. Opening passage:
臣闻求木之长者,必固其根本;欲流之远者,必浚其泉源 - 'I have heard that one who wishes a tree to grow tall must first make firm its roots; one who wishes a stream to flow far must first dredge its source.' Wei Zheng was famous for remonstrating bluntly with Emperor Taizong - and being heeded.