What is the principle of Yang's Shayuan ointment in treating diseases?

The so-called "grasping, pulling, communicating and living" respectively refer to

Grasp: grasp the key points, close to the skin, open pores and open bones.

Pull out: pull out the toxin, dispel wind and cold, and the meridians are unobstructed. The general principle is painless.

Tong: dredging meridians to relieve stagnation, dispersing accumulation and discharging, softening and resolving hard mass, and removing coke.

Activities: promoting blood circulation, dredging collaterals, harmonizing yin and yang, harmonizing qi and blood, and preserving health.