The mind should be calm. If it is not, one cannot concentrate, and when the arm is raised, (whether) forward or backward or back, left or right, it is completely without certain direction. Therefore it is necessary to maintain a calm mind. In beginning to move, you cannot control (it) by your self. The entire mind must (also) experience and comprehend the movements of the opponent. Accordingly, when (the movement) bends, it straightens, without disconnecting or resisting. Do not extend or retreat by yourself. If my opponent has li (strength), I also have li, but my li is previous (in exact anticipation of his). If the opponent does not have li, I am also without it (li), but my mind is still previous. It is necessary to be continually mindful; to whatever part (of the body) is touched the mind should go. You must discover the information by non-discrimination and non-resistance. Follow the method, and in one year, or half a year, you will instictively find it in your body. All of this means use i (mind), not chin (internal force). After a long time the opponent will be controlled by me and I will not be controlled by him.
Red: from Five Character Secret
Reference: T’Ai Chi Ch’Uan Ta Wen, Questions and Answers on T’Ai Chi Boxing Chen Wei-Ming ( Benjamin Pang Jeng Lo & Robert W. Smith ) North Atlantic Books 1985