In motion the whole body should be light and agile with all parts of the body linked as if threaded together. The chi should be excited; the shen should be internally gathered. The postures should be without defect, without hollows or projections from the proper alignment; in motion the form should not become disconnected. The jing should be rooted in the feet, generated from the legs,  
  controlled by the waist, and manifested through the fingers. If correct timing and position are not achieved, the body will become disordered and will not move as an integrated whole; the correction for this defect must be sought in the legs and waist. The principle of adjusting the legs and waist applies for moving in all directions; upward or downward, advancing or withdrawing, left or right. All movements are motivated by mind, not external form.  
  If there is up, there is down; when advancing, have regard for withdrawing; when striking left, pay attention to the right. If the mind wants to move upward, it must simultaneously have intent downward. Alternating the force of pulling and pushing severs an opponent's root so that he can be defeated quickly and certainly. Insubstantial and substantial should be clearly differentiated. At any place where there is insubstantiality, there must be substantiality; Every place has both insubstantiality and substantiality.  
This is a Carbon Neutral website - you should COCO The whole body should be threaded together through every joint without the slightest break. Tai chi chuan is like a great river rolling on unceasingly. Wardoff, rollback, press, squeeze, pluck, split, elbow, shoulder are equated to the Eight Trigrams. The first four are the cardinal directions; the second four are the four corners Advance, withdraw, look right, look left and central equilibrium are equated to the five elements: metal, wood, fire, All together these are termed the Thirteen Postures.