to the opening of hostilities between the Holy Roman Empire and France and returned to the University of Leuven. He completed his studies there and graduated the following year. His doctoral thesis, Paraphrasis in nonum librum Rhazae medici Arabis clarissimi ad regem Almansorem, de affectuum singularum corporis partium curatione, was a commentary on the ninth book of Rhazes. Medical career and accomplishments On the day of his graduation he was immediately offered the chair of surgery and anatomy (explicator chirurgiae) at the University of Padua. He also guest-lectured at the University of Bologna and the University of Pisa. Prior to taking up his position in Padua, Vesalius traveled through Italy and assisted the future Pope Paul IV and Ignatius of Loyola to heal those afflicted by leprosy. In Venice in 1542 he met the illustrator Johan van Calcar, a student of Titian. It was with van Calcar that Vesalius published his first anatomical text, Tabulae Anatomicae Sex, in 1538. Previously these topics had been taught primarily from reading classical texts, mainly Galen, followed by an animal dissection by a barber–surgeon whose work was directed by the lecturer. No attempt was made to confirm Galen's claims, which were considered unassailable. Vesalius, in contrast, performed dissection as the primary teaching tool, handling the actual work himself and urging students to perform dissection themselves. He considered hands-on direct observation to be the only reliable resource. Vesalius created detailed illustrations of anatomy for students in the form of six large woodcut posters. When he found that some of them were being widely copied, he published them all in 1538 under the title Tabulae anatomicae sex. He followed this in 1539 with an updated version of Winter's anatomical handbook, Institutiones anatomicae. In 1539 he also published his Venesection Epistle on bloodletting. This was a popular treatment for almost any illness, but there was some debate about where to take the blood from. The classical Greek procedure, advocated by Galen, was to collect blood from a site near the location of the illness. However the Muslim and medieval practice was to draw a smaller amount of blood from a distant location. Vesalius' pamphlet generally supported Galen's view but with qualifications that rejected the infiltration of Galen. In Bologna, Vesalius discovered that all of Galen's research was restricted to animals, since the tradition of Rome did not allow dissection of the human body. Galen had dissected Barbary