溯流穷源

Explanation: Su: upstream. River upstream to find the place originated. The root metaphor for something. 　　Source: Mingxie Zhao Zhe, "something the Department of the Second Five Miscellaneous ZU": "Spring and Autumn Period, the good name of who has the public Zhong Lu, Xu Chen Jin has, Zhengyou Zi Yu, and other free thinkers, said Yan. Upstream poor source, if Sri Lanka is also the difficulty. " 　　Examples: However, it is a compilation recorded by the Han Chinese prose, is eight Tang album. Ancient Order of school governance to serve those who, come the Jin Liang, then be ~, to do all the fine family Yun ears. ★ Qing Fang Bao, "Classical cases about election procedures" Thesaurus:  Suliucuyuan, Suliuqiuyuan