Page from a 9th or 10th century Italian edition of 'De Medicina,' a 1st century medical treatise by Celsus. Aulus Cornelius Celsus (25 BC-50 AD) was a Roman encyclopedist, known for his extant medical work, De Medicina. De Medicina (On Medicine) is the only surviving section of a much larger encyclopedia, a primary source on diet, pharmacy, surgery and related fields concerning medical knowledge in the Roman world. On Medicine is divided into eight books: 1) the History of Medicine, 2) General Pathology,3 ) Specific Diseases, 4) Parts of the Body, 5) and 6) Pharmacology, 7) Surgery and 8) Orthopedics. The lost portions of his encyclopedia likely included volumes on agriculture, law, rhetoric, and military arts.