Tao Teh Ching Chapter 33

知人者智，自知者明。胜人者有力，自胜者强。知足者富。强行者有志。不失其所者久。死而不亡者寿。

Translation
He who knows others is smart, he who knows himself is enlightened; He who overcomes others has got strength, he who overcomes himself is truly strong; He who satisfies on what he has is rich; He who acts with brutal force has got ambition. He who does not lose his place will last. He who perishes but does not die has got longevity.

Comments
The psychologist’s job is to know others. We want to know others. We are called considerate when we understand others. We are smart and sharp if we know others. This is all right. But Lao Tzu says to know oneself is more. This is virtually the same as the yogic path of self-realization leads to enlightenment.
A champion wrestler is physically strong; he can defeat anyone on his path. However he suffers from depression and eventually committed suicide. Who defeated him? The answer is himself.
强行者有志。 What is ambition? In this society, ambition is not a negative word. We see ambitious people. Even in yoga classes we see them. We are told many times by our teachers that we cannot act with brutal force with our practice, and that we need to be slow. We need to cut our ambitions. This is easy to say but quite difficult to implement. Coming back to Chapter 15, Lao Tzu asked: 孰能浊以静之徐清？孰能安以动之徐生？
Who can clarify the troubled waters by allowing it to settle down quietly? Who can give life to the motionless by gently stirring?
不失其所者久。 To truly know oneself means he knows where he belongs and therefore he cannot lose it.