《后汉书·列传·皇甫嵩朱俊列传》
如果想辅不能辅佐的朝廷，雕刻朽败的木头，如同上坡走泥丸，迎风行船，难道是容易的吗？
若欲辅难佐之朝，雕朽败之木，是犹逆坂走丸，迎风纵棹，岂云易哉？
If you want to assist the court that cannot be assisted, and carve decayed wood, it is like walking uphill on a mud pill and sailing in the wind. Is it easy?