Hermann Ludwig von Helmholtz, the German physiologist and physicist, was born in Potsdam and educated at the Potsdam Gymnasium, where his father taught philology and classical literature, and at the Royal Friedrich-Wilhelm Institute of Medicine and Surgery in Berlin, from which he graduated as a doctor of medicine at the age of twenty-one. Helmholtz's outstanding scientific talent led to the curtailment of his required ten-year service as a Prussian army physician and surgeon. After the presentation and publication of his famous paper Über die Erhaltung der Kraft (On the conservation of energy) in 1847, he held only academic posts. He was instructor in anatomy at the Academy of Arts in Berlin (1847–1848), professor of pathology and physiology at Königsberg (1848–1855), professor of physiology and anatomy at Bonn (1855–1858), professor of physiology at Heidelberg (1858–1871), professor of physics at Berlin (1871–1888), and the first president and...