What's the use of seals for people and books?

The seal of "people and calligraphy are mediocre works" should be a casual chapter, which is used by the owner (or signer) of the seal to engrave his own calligraphy works. Seal script is intended to be humble that both people and calligraphy are mediocre, in which "book" refers to calligraphy, "all" is equivalent to "all" and "mediocrity" refers to mediocrity. People often praise people who are old and have profound calligraphy accomplishments as "people and books are old", and "people and books are mediocre" is the language used to claim that talent and calligraphy are ordinary but not outstanding. It is a sign of modesty and self-restraint for the author to affix this casual stamp on calligraphy works.

Leisure chapter refers to the seal other than name, study, official position and books. It evolved from auspicious seals in Qin and Han Dynasties. Besides auspicious words, poems, aphorisms and self-disciplined words are often engraved. Artists who specialize in seal cutting, painting and calligraphy generally have many seals, among which, except the name and font size, other seals are collectively referred to as "idle printing" in printing science. For example, Qi Baishi, who was born as a carpenter, often stamped the leisure seals of "Mujushi", "Lubanmen" and "Carpenter's Gate" on his paintings and calligraphy to show his unique experience. Xu Beihong has a "spotless" leisure chapter to show his mind; On Li Keran, there is a "white-haired boy student" to show his old and studious mentality. Wait a minute.