Li Yan, a top student in engineering mechanics, accidentally traveled to the Wei River in Guanzhong in the 15th year of Zhenguan, and started a completely different life as a refugee with amnesia. With knowledge of modern science, he started with a simple water filter to solve the problem of drinking water pollution in the village and the lever principle of repairing the water wheel. He won the trust of his neighbors with his wisdom beyond the times.
From the innovation of agricultural tools in the Jingyang County workshop to the engineering pioneering project overseen by Chang'an General, he used geometric knowledge to optimize agricultural tools, improved trebuchets using mechanical principles, resolved resource disputes with water conservancy calculations, and challenged traditional arithmetic understanding with decimals. From the Wei River dams to the long-distance water system, from the permafrost fortresses on the Xueyantuo battlefield to the honeycomb-style beacon towers, he integrated modern engineering thinking into the texture of the Zhenguan era.
He discussed war with Li Jing, met Emperor Taizong to analyze theory, and discussed the transportation of military rations with Xu Maogong. Amidst the fierce battles and fireworks in the market, he used distillation to purify medicinal materials and met the military doctor Su Wan. He used the lime method to improve papermaking and compiled geometric maps to cultivate technological sparks. In the end, this modern science student put aside his desire to return home and built the Tang Dynasty's first research laboratory in Zhongnan Mountain. He used his knowledge to inject the glimmer of science and technology into the prosperous era of Zhenguan, and wrote an innovative legend of the intertwining of science students and the prosperous Tang Dynasty.
