(Bruce Lee's handwritten essay from one of his courses at the university of Washington.
Gung fu is a special kind of skill, a fine art rather than just a physical exercise. It is a subtle art of matching the essence of the mind to that of the techniques in which it has to work. The principle of gung fu is not a thing that can be learned, like a science, by fact-finding and instruction in facts. It has to grow spontaneously, like a flower, in a mind free from emotions and desires. The core of this principle of gung fu is Tao - the spontaneity of the universe. After four years of hard training in the art of gung fu, I began to understand and felt the principle of gentleness - the art of neutralizing the effect of the opponent's effort and minimizing the expenditure of one's energy. All these must be done in calmness and without striving. It sounded simple, but in actual application it was difficult. .
The moment I engaged in combat with an opponent, my mind was completely perturbed and unstable. And after a series of exchanging blows and kicks, my theory of gentleness was gone. My only thought at this point was "Somehow or other I must beat him and win!" .
My instructor at the time, Professor Yip Man, head of the wing chun school of gung fu, would come up to me and say "Leung(Lee's Chinese nickname was Lee Siu Leung), relax and calm your mind. Forget about yourself and follow the opponent's movement. Let your mind, the basic reality, do the counter-movement without any interfering deliberation. Above all, learn the art of detachment." .
"That was it!" I thought. "I must relax!" However, right then I had just done something that contradicted against my will. That occurred at the precise moment I said, "I must relax." The demand for effort in must was already inconsistent with the effortlessness in relax. .
When my acute self-consciousness grew to what the psychologists refer to as the "double-blind" type, my instructor would again approach me and say, "Leung(pronounced Loong), preserve yourself by following the natural bends of things and don't interfere.