It means: keep your breath steady and your expression focused.
Said by: On the Pen by Cai Yong.
The full text is as follows:
The books are scattered. If you want a book, you have to put it down, put it down, and then write. If forced by the environment, Zhongshan rabbit is luxurious,
It can't be good Husband's book, first sit quietly and meditate, feel at ease, say nothing, get angry and lose interest, and be mysterious and colorful. If it's for the supreme, it's all wrong.
Translation:
Calligraphy is a distraction. Before you start writing, you should relax and feel free before you start writing. If you are forced to write by business, even if you have a good pen like Zhongshan Rabbit, you can't write good words. When writing, you should sit still, be calm, don't talk to others, and look absorbed, as if facing the supreme. It is impossible to write badly.