How the hip moves: Important!

In an article written by Sam Masich:

Here is another possible reason that the legs are mentioned in the classics and not
the hips. The hips should always move as a natural consequence of actions initiated
in the legs (not the torso). Since they (hips) have no mechanism by which to move in and of themselves, it is an error to think that we move from our hips. Like a tree being swayed by the wind, the hips are caused to move. An ignorance of this critical concept has left somepractitioners struggling for decades, trying to find root, fluidity and true stickingability.

The hips must allow movement. They must acquiesce to pressure, letting force, movement and energy transfer up, down, forward, backward and side to side. While the pressure may come from the opposite leg¹s driving force or from a partner¹s pushing, the hips themselves must remain receptive, passive and clear. 

We do not try to move the hips in relation to force but, like the axle of a wheel, allow
them to rotate as a matter of course. This is often described as folding the hip or kua.

Note:  Sam Masich is a much respected Internal Martial Artist. I have had the very good fortune to attend workshops held by Sam at the Tai Chi Farm.