Scientific medicine survived the Dark Ages in the West chiefly through Jewish physicians, who circulated Greco-Arabic medical knowledge in Christendom; through the Byzantine culture of southern Italy; and through translations of Greek and Arabic medical treatises into Latin. The original European medical center was the School of Salerno, but after A.D. 1268 the University of Naples became more prominent. Roger of Salerno, recommended seaweed (rich in iodine) for goiter in 1180 and gold was imbibed to "comfort sore limbs", foreshadowing modern gold therapy for rheumatoid arthritis. Other famous 13th century physicians were Arnold of Villanova and Guglielma Salicetti, professor of medicine at Bologna. The latter made notable improvements in his Chirurgia in a 1275 edition, associating surgical diagnosis with a knowledge of internal medicine, using careful clinical records, showing how to suture a divided nerve and advocating the knife rather than the cautery, which had been popular with the Moslems.
To obtain a medical license under Frederick II one had to take a three year course in scientia logicalis, then study medicine at an approved school for five years, passtwo examinations and then practice for a year under the supervision of an experienced physician.