一个人的人际关系怎样，便知道他是一个怎样的人。
People are known by the company they keep.

只知道自己不做坏事，不知道别人会做坏事，这样的人难免要吃大亏。
Such a person will inevitably suffer heavy losses who only knows not be evil himself ,but does not know that others would do evil.