源頭活水yuán tóu huó shuǐfountainhead and river source—motive force; source
? 生活是文藝創(chuàng)作的～。Life is the source of literary and artistic creation.
? 問渠那得清如何？為有～來。(朱熹《觀書有感》) If you ask why the canal is so clear?|Because the flowing water has come from the waterhead. |