Canon of Medicine by Avicenna
This book is a five-volume medical encyclopedia written in the 11th century. It provides a complete system of medicine according to the principles of Galen (and Hippocrates). The work covers all aspects of human health, including diagnosis, treatment, and prevention of disease, as well as pharmaceutical sciences and the use of medicinal plants. It was used as a standard medical textbook in the Islamic world and Europe for centuries and has had a lasting impact on the field of medicine.