Nothing is known about the life of Celsus, including whether his praenomen is Aurelius or Aulus, though historians believe it is the latter. Nobody knows where Celsus lived, although it is believed that he lived in Gaul. What is known about Celus is that he put together a huge encyclopedia during the reign of Augustus or Tiberius. What is known about the life and times of Celsus comes from De Medicina, the lone surviving part of what was apparently a huge encyclopedia put together by Celsus on all sorts of topics, including agriculture, military science, philosophy and law. It is unclear whether Celsus was even a doctor, but it drew upon all of the medical knowledge of the Ancient Greeks. De Medicina covers topics including diet, disease, pharmacology, therapy and surgery. Sections detail the removal of missile weapons, stopping bleeding, preventing inflammation, diagnosis of internal maladies, removal of kidney stones, the amputation of limbs and more. De Medicina was known during the Middle Ages, but was later lost up until the 15th century. It was the first medical book to be printed, in Florence, 1478.