Li Shizhen was a famous medical scientist in Ming Dynasty .He was born in 1518 .He wrote a famous book “Ben Cao Gang Mu” ,which is a collection of Chinese herbs .It included 2000 Chinese herbs with millions of characters .He visited mountains ,called on ordinary people ,tasted different kinds of herbs and even did experiments on himself .It took him 37 years to finish the book .The book is considered to be a great contribution to the development of Chinese medicine .