War is the father of all, and king of all; and some he has made gods, and some men; some he has made slaves, and some free.
孔子说:“经常学习,不也喜悦吗?远方来了朋友,不也快乐吗?得不到理解而不怨恨,不也是君子吗?”
Psychological truth is found in practical experience.