Guo Pu (276-324) was a noted natural historian and also a versatile and prolific writer of the Eastern Jin Dynasty (317-420).

Guo Pu made annotations to many Chinese ancient works, such as Erya and Shan Hai Jing (Classic of Mountains and Seas). In the Annotations to Erya, the earliest work of Annotations in China, he gave vivid descriptions to animals and plants.

The term "Erya" means "approach to the proper". It has been called the earliest Chinese dictionary dating from the 3rd century BC. The book is an encyclopedia-dictionary, describing more than 590 kinds of animals and plants. It has 19 sections, with the last seven on grasses, trees, insects and reptiles, fish, birds, beasts and domestic animals. However, the book is difficult to understand as it was written in ancient texts.

It took Guo Pu 18 years to study the book and finish Annotation to Erya. Guo's annotation made Erya an important reference book on the study of herbs.

Guo Pu was also the first person who used a great number of pictures while making annotations to animals and plants. Pictures have become an important part in all major herbal books since the Tang Dynasty (618-907).