Nicolaus Copernicus (1473-1543), an internationally recognized Polish astronomer, studied liberal arts at the Jagiellonian University in Cracow during the period 1491-1495. Shortly thereafter he was sent by his uncle to Bologna University, where he spent almost 5 years (1496-1501) studying law and philosophy. After his return to Poland, Nicolaus was nominated as canon in the cathedral chapter in Frombork. Next he started to study medicine in the University of Padua, one of the best-known centers of medical education in Europe. He was granted a bachelor degree and after another year, a therapeutic license (veniam practicandi), but never obtained his doctoral degree from Padua, though he was always called doctor of medicine ("medici doctor"). Copernicus returned to Warmia in 1503 and spent almost 40 years there. During the first few years he was the personal "medicus" and secretary of his uncle, Bishop Lucas Watzenrode. After the death of his uncle in 1512, Copernicus became the personal physician to the subsequent 4 Warmian bishops and his confreres from the Warmian chapter in Frombork. Copernicus practiced medicine not only in diagnosing and taking care of his patients but also in personally preparing the prescribed drugs. He was often consulted (consiglia) from several other cities, including Gdańsk, Königsberg, Lubawa, Elblag and Olsztyn. He also collaborated and consulted with Jan Benedict Solfa and Laurence Wille, the official Polish royal physicians at the time. During the epidemics of 1519, Copernicus employed sanitary preventive measures by providing several Warmian and Pomeranian towns with an innovative water supply system. Copernicus is well known as a genius in astronomy, but this great Renaissance man was also a mathematician, engineer, soldier, writer, economist and, last but not least, a practicing physician.