Who knows the origin of the evil sword manual and sunflower manual in "The Swordsman"?

In Chapter 30 of "The Swordsman": Secret Discussion.

"Evil Sword Manual" is a name that Du Yuan changed when he got the fragment of "Sunflower Book" to avoid being noticed. No one has ever successfully practiced the "Sunflower Book". Later, it was collected by Zen Master Hongye of the Putian Shaolin Temple. Zen Master Hongye never understood the secret of the book, so he never practiced it.

Because the internal strength in the book is completely different from the general internal strength, normal people cannot understand the reason for the rapid growth of internal strength. On the other hand, the moves are too weird and inconsistent with normal martial arts principles.

Extended information

There are two versions of the creation method of "Sunflower Collection" in Jin Yong's novels.

1. In the earliest version, "Sunflower Collection" was co-authored by a man and a woman. The man's name has the word "Kui" in it, while the woman's name has the word "Hua" in it, hence the name "Sunflower Collection". This man and woman were originally a loving couple, but later turned against each other due to circumstances, and the half of the book they created was even more mutually restrained.

The "Sunflower Book" is therefore divided into two halves, one for cadres and one for Kun. Some people in the world also call it "Book of Heaven, Book of Earth", "Yin Lu, Yang Lu". In the early version, the "Sunflower Collection" was closely related to the "Zixia Gong" of the Huashan School. Youdao said, "The Zixia Secret Book is the beginning of entry. The Sunflower Collection is the peak."

2. After Jin Yong revised the novel, "Sunflower Collection" was changed to be created by a palace eunuch, but no one knows why such a master would serve as a palace eunuch. Although the "Sunflower Book" is profound, it leaves many difficult questions for future generations to answer. However, how this secret book spread among the people is unknown.

Baidu Encyclopedia--Sunflower Collection