This English translation is based on an Arabic critical edition compiled by a team scholars at Hamdard University, India, by comparing early copies of original Arabic source materials. Book I of the Canon covers the principles of Four Humors (Greek/Arabic/Unani) medicine, as well as an overview of anatomy from the point of view of that system. It is a practical book, with sections on pulse diagnosis and urinalysis, and on therapeutic regimens for various ages and conditions, in health and in disease.