What is the Book of Changes about?

The Book of Changes includes 64 hexagrams, hexagrams' names, hexagrams' words, 384 hexagrams, hexagrams' names and hexagrams' words.

Because everything in it is a basic binary relationship, such as yin and yang, positive and negative, height, length and so on, different people study it and see different contents. For example, learning philosophy sees the unity of opposites and says it is a philosophy book; Those who study natural science see 0, 1 and say it is binary; Fortune tellers look at life and death and say that this can tell fortune; People who play geomantic omen can see good and bad luck, which can be seen in geomantic omen. Politicians see the relationship between strength and weakness, saying that this is an official classic; I saw the yin and yang inside, concave and convex, saying it was a treasure house of sex; ………………

So it became an encyclopedia.