Xiao Tian entered the cave and saw a stone statue that looked almost alive. He admired the craftsmanship for a while before beginning his search for martial arts manuals. Shortly afterward, he found the two manuals, Northern Darkness Divine Art and Lingbo Weibu.
Xiao Tian opened the Northern Darkness Divine Art and saw what was written on the first page: "The divine art of the Xiaoyao Sect: 'North of the barren expanse lies a dark sea, the Pool of Heaven. There is a fish therein, thousands of li in breadth, and none know its length.' It also says: 'If water does not gather deeply enough, it lacks the strength to bear a great boat. Pour a cup of water into a hollow in the hall, and a blade of grass may serve as a boat; place the cup there, and it will stick fast. The water is shallow, yet the boat is large.'"
Therefore, the first essential principle of our sect's martial arts is the accumulation of internal energy. Once one's internal energy is sufficiently deep, every martial art under heaven may be used for one's own purposes. Just like the Northern Darkness, it carries every large and small vessel, and contains every great and small fish.
Yet neither Xu Zhu nor Duan Yu in the original work had grasped the true essence of the Northern Darkness Divine Art. Though both cultivated Northern Darkness true qi, Duan Yu had learned the Northern Darkness Divine Art but only scratched its surface. Although he could absorb others' internal energy, he did not know how to use it. While Xu Zhu possessed the Northern Darkness true qi formed from Wuyazi's lifetime of internal energy, Xu Zhu himself did not know the Northern Darkness Divine Art. This could be seen from the fact that