An essay on the Taiji Quan Lun (attributed to its legendary creator Zhang San Feng 张三丰)
The root is in the feet, issuing relies on the legs, control is in the waist, and expression is in the extremities. This flow is performed simultaneously, in a unified movement.
Coordination and harmony ensure the quality of the (martial) force/energy release
Energy ascends and goes through each body part until its release. When releasing through the hands, the move is initiated from the ground, and thus the legs guide the trunk, the shoulders guide the arms, and the arms guide the hands. Energy has a direction, but it is imperative for the whole to be unified: everything activates simultaneously, in harmony (and not the legs first then the waist than the arms).