Felix Klein

Felix Christian Klein was born 25 April 1849 in Germany and trained in an era when geometries were proliferating - Euclidean, hyperbolic, projective - with no clear framework to relate them. In 1872 he published the Erlangen program, which classified geometries by their underlying symmetry groups and synthesized much of contemporary mathematics in one stroke. His work spanned group theory, complex analysis, and the deep ties between algebra and shape. At Göttingen he built an institution: new chairs, new institutes, seminars that covered nearly every branch of mathematics and its applications. He spent decades pushing reform in math education across Germany and beyond, and in 1908 became the first president of the International Commission on Mathematical Instruction at the congress in Rome. He died 22 June 1925, having reshaped both the map of geometry and the ground on which it was taught.