Felix Klein

Felix Klein was born in Düsseldorf in 1849 and studied in Bonn, where he worked closely with Julius Plücker. After taking his doctorate, he joined the circle of young mathematicians associated with Alfred Clebsch in Göttingen. He then briefly visited Berlin, where he befriended Sophus Lie, with whom he struck up an important collaboration. They spent the spring of 1870 together, up until Klein’s hasty departure with the outbreak of the Franco-Prussian War. Klein then returned to Göttingen, but already in 1872 he was appointed professor of mathematics in Erlangen. Lie joined him there and contributed to what later became Klein’s single most famous work, the so-called “Erlangen Programm” [Klein, 1921-1923, p. 460-497], in which he surveyed recent trends in geometry from the point of view of their associated transformation groups.