Wisdom in four words

Chinese proverbs - usually four character long idioms - are developed from the formulaic or social dialect, saying, expression and historical story in Chinese. Some proverbs are literary, that is, from a written source. Here are some examples:

An inch of time is an inch of gold but you can't buy that inch of time with an inch of gold.

A fall into a ditch makes you wiser.

Have a mouth as sharp as a dagger but a heart as soft as tofu

If you have never done anything evil, you should not be worrying about devils to knock at your door.