The renown of the philosopher who had gone to Constantinople to study Greek and could read Aristotle and Galen in the original, the glory of the scholar who taught medicine at Paris and was regarded there as a great master, all this spread his fame throughout the Western world. The University of Bologna occupies a very important position in the history of medicine. Fifteenth-century medicine exhibits a notable progress, especially in the literature on personal hygiene, impelled thereto by the cruel necessities of the plague. Frederick II, also, recognized the importance of the school of Salerno and promulgated stringent laws for the study and practice of medicine. The knowledge of surgery in the later centuries of the Middle Ages was considerably influenced by Greek and Byzantine traditions, as well as by the writings of the Arabs and the school of Salerno.