It means that it is usually a metaphor for the secret of nature, and it is also an important secret that cannot be revealed; The name of the star is Dousu; State secrets; It's still mental. It's called natural brain waves.
This sentence comes from the Book of Changes, which means: Between heaven and earth, the law of the operation and development of things is always fifty, and only forty-nine can be deduced, one of which is a secret! In real life, secrets are actually around us, but when they appear less and are not easy to be detected, it will make people feel that secrets are difficult to be discovered!
Extended data:
The Book of Changes refers to Lianshan, Ghost Stories and Zhouyi. Among them, Lianshan and Guizang have been lost, and there is only Zhouyi in the world. In "Twelve Years of Zuo Gong", King Chu Ling praised Zuo's leaning item: "Good history, good reading, can read three graves, five classics, eight articles and nine hills."
The Book of Changes is essentially a book about changes, which has long been used as "divination". Later generations know more about his philosophy, thus becoming a profound dialectical philosophical work. "Divination" is to predict the development of future events, and The Book of Changes is a book that summarizes the laws and theories of these predictions.
The Book of Changes is an outstanding representative of China culture. Vast, subtle and all-encompassing, it is also the source of Chinese civilization. Its content involves philosophy, politics, life, literature, art, science and many other fields. It is the first of the group classics and a classic of Confucianism and Taoism.