Yehe’s decades of hard work is an excellent introduction to and refinement of Six Yao. To fully understand it, you need to read it carefully. The theoretical part of the book is very clear, the assertions are to the point, and the author has a truth-seeking attitude. He makes up for what is unclear again and again, which is very valuable and teaches people the right path. However, this book contains almost no image-taking part and cannot meet modern people's requirements for hexagrams. This is a flaw.