What are the "five forms" of calligraphy lines?

The so-called "five styles" of calligraphy lines refer to:

A line of bones, tendons, veins, meat and skin are indispensable. If they are divided into five parts, they will be one.

Bone: refers to the appearance of strong lines and strong momentum.

Tendons: refers to the appearance of tight lines and muddy strength.

Pulse: refers to the rich and vivid appearance of lines.

Meat: refers to the plump and elastic appearance of lines.

Skin: refers to the smooth, clear and bright outline of lines, which plays the role of wrapping flesh and blood without exposing bones and muscles.

Calligraphy lines require five forms, but also need symmetry and coordination, otherwise the lines will lose their beautiful texture and enjoyment. In addition, the line shape is the carrier of ghosts and gods. If the five elements are not prepared, there is no way to talk about meaning and charm.