John XXI, the Pope Philosopher and Physician-Scientist of Portuguese Origins Died of Crush Syndrome in 1277.

The aim of this work is to refer on the death due to crush syndrome in 1277 of Pope John XXI, philosopher, logician, anatomist, physician scientist, university professor of medicine at the university of Siena and author of books adopted for nearly 4 centuries in universities in the Middle Ages. The Pope died crushed by the ceiling of his office which had been built in rush to meet his need for a quiet and warm place, his need of light and nature. There he attended to his duties of governing the church, studied fine theological questions, inspected the stars, made experiments and discussed with the renowned ophthalmologists who in those days made Viterbo the center of the study on vision.