The Compendium of Materia Medica is written by Li Shizhen, a famous medical scientist in the Ming Dynasty. With almost 2 million Chinese characters, the book lists 1,892 kinds of medical substances. Besides Chinese herbal medicines, it includes animals and minerals used as medical substances. The Compendium of Materia Medica is regarded as the most complete medical book in the history of traditional Chinese medicine. Detailed introductions of all the medical substances are given in the book, including name, smell, appearance, etc. It has been translated into more than 20 languages and spreads all over the world. Even now it is still often used as a reference book in medicine.