The Unfinished Calculation

In the 23rd year of Zhenguan, Li Chunfeng sat on the Star Observation Platform at Fengming Mountain for seven days and seven nights. On the morning of the eighth day, he said to his disciple: "A thousand years from now, the thing underground will awaken. I can seal it, but not forever." He traded seven years of his life for a needle, a copper coin, and a contract with an expiration date. The needle pierced the coin's hole, with a term of a thousand years. From then on, the Li family guarded it for nineteen generations, spanning thirteen centuries. No one knew that on the same night of that same year, Yuan Tiangang, in the room next door, quietly broke the 61st image of the Tuibei Tu. That image was the ultimate prophecy. With a single palm strike, he hid the truth in a lock that only the bloodline of the Yuan family could open. Then he said to his son: "The Yuan family must guard this lock for generations. Let no one open it—including ourselves." But the lock was not kept. By the 17th generation, the guardian Li Shouzhen desperately repaired the cracks during a special era, enduring until the eve of the millennium, leaving behind a final message: "The thing in the needle's eye has awakened." By the 18th generation, the guardian Li Xuanping discovered secrets within the Tianji Pavilion, went alone to investigate, and disappeared for twenty years. By the 19th generation—on the night of the millennium, the year 2000, Li Chengyuan stood on the Star Observation Platform at Fengming Mountain. — Description from novelcodex.org