 In 1809, Schopenhauer began studies at the University of Göttingen, where he remained for two years, first majoring in medicine, and then, philosophy. In Göttingen, he absorbed the views of the skeptical philosopher, Gottlob Ernst Schulze (1761–1833), who introduced him to Plato and Kant. Schopenhauer next enrolled at the University of Berlin (1811–13), where his lecturers included Johann Gottlieb Fichte (1762–1814) and Friedrich Schleiermacher (1768–1834). His university studies in Göttingen and Berlin included courses in physics, psychology, astronomy, zoology, archaeology, physiology, history, literature, and poetry. At age 25, and ready to write his doctoral dissertation, Schopenhauer moved in 1813 to Rudolstadt, a small town located a short distance southwest of Jena, where he lodged for the duration in an inn named Zum Ritter. Entitling his work The Fourfold Root of the Principle of Sufficient Reason (Über die vierfache Wurzel des Satzes vom zureichenden Grunde), it formed the centerpiece of his later philosophy, articulating arguments he would later use to criticize as charlatans, the prevailing German Idealistic philosophers of the time, namely, his former lecturer, J. G. Fichte, along with F. W. J. Schelling (1775–1854) and G. W. F. Hegel (1770–1831). In that same year, Schopenhauer submitted his dissertation to the nearby University of Jena and was awarded a doctorate in philosophy in absentia. 