源头活水yuán tóu huó shuǐfountainhead and river source—motive force; source
❍ 生活是文艺创作的～。Life is the source of literary and artistic creation.
❍ 问渠那得清如何？为有～来。(朱熹《观书有感》) If you ask why the canal is so clear?|Because the flowing water has come from the waterhead. |