For the next 30 years, he was roaming between the mountains looking for medical herbs. He interviewed people. He collected almost all the different kinds of herbs. Then, he drew detailed sketches of them. At last, Li Shizhen finished his masterpiece – Bencao Gangmu at the age of 60. Have a long-term vision and a sense of responsibility for the country. He quit his job and returned to his hometown, for he wanted to help more people. In his spare time, he began to work on what was to become Bencao Gangmu – his guide to the medical use of herbs