In “Uniformity of All Things”, written by Chinese philosopher ZhuangZi, it says “Once the hinge start rests in its circle, it can respond limitlessly.” “Hinge” means the door hinge. If there is a center, you can create circles around it; if you want to create circles, you must have a center. In TaiChi, “hinge” is the center line of our body; the circles can be created from this center line. They can be big or small, can be in all directions. If you can reach the opponent’s center line, you can be in control of that person’s body; only if you build a strong center line for yourself,  you can create circles limitlessly.