"If you miss by a hairsbreadth , you miss by 1000 miles" by Wang Zhongyue - Taijiquan Lun
The line from the Taijiquan Lun by Wang Zhongyue " if you miss buy a hairsbreadth , you missed by 1000 miles" can only be understood when one starts to understand what is meant by being in Center. When the body is in Center, then the tissue is neutral and has no unauthorized contractions. A neutral posture will more easily ground out someone's force causing their force to hit the floor. Most practitioners play a game of hide and seek when it comes to push hands training. Most practitioners do not understand that if their posture is correct , it will neutralize or transform the force of your opponent. This is known as Hua Jin or transforming energy. When the posture is neutral, then the tissue is at its softest and allows the Qi to flow through easily. The posture will have muscular tension if there are any contrivances in it's formation. The following is an example showing the parrying hand used in the posture brush knee and twist step. It shows that if the arm is twisted in either direction or above or below its body center , that it will fail allowing the force to cause my partner or opponent to be pushed out or collapsed. When the posture is correct it automatically grounds out my opponent's force which loads my Jin. This is how you transform your opponents force into a re-action force that is of their own making. This skill typically develops after years of standing training and song gong training. When I am in the correct position it does not take any additional muscles to stay comfortable. My Qi is not severed ; In fact I can actually start to relax and feel more stable. This is an example of what it means to "miss by a hairsbreadth and you miss by 1000 miles"