As for the reason, we should explain it from the most basic yin and yang.

People in China believe that Yin and Yang are the foundation of all things.

Repetition of yin and yang is three talents.

That is, heaven and earth are the three results of yin and yang metaplasia, namely pure yang, pure tone, half yin and half yang! Four images, five elements, etc. No one came out from behind, but they didn't escape from this cage! And six hexagram is no exception! From this point of view, the basis of six hexagrams is yin and yang, which can transform everything and deduce the generation of everything in reverse! However, this is not something that ordinary people can deduce! The amount of calculation is too huge, and it is basically impossible to infer futures! Moreover, the deduction of six hexagrams is not as simple as expected, because the deduction of one thing is actually not difficult! Take one plus one equals two, everyone can calculate, and everything can be understood as one plus one equals two, but interestingly, when countless ones plus one are combined together, the amount of calculation is very huge, because there are too many things involved! I don't know if you can understand this! Because of time, my explanation may be vague. If you are interested, you can discuss it slowly!