Title of
贾岛《
寻隐者不遇》 (Jia Dao, Tang, 9th c.), 20 characters that sketch a whole encounter:
松下问童子，
言师采药去。
只在此山中，
云深不知处 (Beneath the pine I asked the boy; he said his master was off gathering herbs. 'He's just in these mountains — but the clouds are deep, who knows where'). Model of
言外之意 (meaning beyond words) in Chinese poetry.
