Sinking yields floating causing no letting go, while floating feeling a little resistance, the core always continues that floating changes into sinking without resisting. Thus floating yields sinking.
Follow : floating and sinking follow each other
Adhere, link, follow : lead into emptiness
Stick : release at the correct timing
The basic practice method lies in no letting go and no resisting in the interaction of ward off, roll back, press, and push
Proof: let any one strikes me with thousand pounds; I am able to guide and deflect it with four ounces.
That's why Chang San-feng requires that in motion, all parts of the body must be light, nimble and strung together.