  It was in these years at Vienna that Mach began his interest in physiology. Johannes Müller and his students had started a new school of physiology in the 1840s. Initially centered in Berlin, it came to Vienna following the political reforms of 1848 in the guise of Ernst Brüke and Carl Ludwig, a former a student of Müller. This new school was characterized not just by a general suspicion of vitalism (though Müller remained a vitalist of sorts), but more by an agreement on the importance of the application of physical-chemical methods to the biological sciences. Carl Ludwig, Herman von Helmholtz, and Ernst Haeckel also studied under Müller. Although his degree was in physics, Mach enrolled as a student of the Medical Faculty, taking 22 hours of classes in physiology, chemistry, and anatomy. In 1861 he taught a course in physics for medical students, out of which he developed his textbook, Compendium der Physik für Mediciner. He also published his first article on psychophysics, Über das Sehen von Lagen und Winkeln durch die Bewegung des Auges, where he studied the relationship between tension in the eye muscles and perception of form. This work also contains Mach’s first reference to Fechner, whose influential Elements of Psychophysics was published in 1860. During the next years in Vienna, he also taught classes in psychophysics and a class entitled Die Principien der Mechanik und mechanischen Physik in ihrer historischen Entwicklung, which possibly marks the start of his interest in the history of science (though we do not know the actual contents of the lectures). Mach was also influenced by Helmholtz’s Die Lehre von den Tonempfindungen.