Letter is the meaning of ancient books in China. The first broadcast time is noon and the first broadcast time is midnight, so it is called meridian letter.
In ancient times, some wise men tried to have a definite understanding of the external universe of the living environment of species, which began with the concepts of time and space, namely space and time. Ancient people thought that the universe was a round celestial body. In order to locate some areas of this celestial body, the meridian is used to represent the "north and south" of heaven and earth, the "child" is due north and the "noon" is due south. In order to determine the change of one day in a day and the change of four seasons in a year, we use "Zi" and "Wu" to establish a time sequence, with "Zi" as the beginning and "Wu" as the center, in which "Jing" represents the connection and continuation of time.
Later, when trying to understand the origin of life, medieval scholars put forward the numerology theory of "heavenly stems and earthly branches's Five Elements", trying to explain the internal relationship with nature and determine the direction of individual life. The combination of "A" and "B" in Tiangan and "Zi" and "Ugly" in Dizhi also produces the meridian. At this time, the meridians have been interpreted as having the meaning of "mutual resistance and conflict", and "Zi" and "Wu" came into being. Extending this contradiction to other things is "positive" and "complementary".
We know that "South" and "North" in space are relative to the beginning and middle of time, and things are relative. And "north and south", "always" and "positive" are interlinked, and the end of the front is also the beginning of the back, which is manifested in the transformation of things. Therefore, "meridian" also means "mutual connection", "mutual restriction" and "mutual supplement"
To sum up, "meridian" is not just space. The concepts of time and numerology also include the relationship and evolution between things. So there are the concepts of meridian, meridian circle, meridian nerve, meridian ridge and meridian boxing.
"Letter", as its name implies, is a genre that simplifies the reading of books. As a tool to promote social progress and personal self-improvement, books have been widely recognized by the society, but reading a book with hundreds of pages takes up a lot of time and energy, and the incoherence of reading will make readers understand and absorb only by impression, and often a book forgets the previous content at the end. Combining practical application, Shujian extracts the core idea of a single book, and makes the contents of the book into an easy-to-understand demonstration document form with concise language and schematic diagrams. Letters not only respects the original, but also temper the original, which enables readers to understand and absorb the essence of the original in the shortest time.