"Mathematics knows no races or geographic boundaries;...the cultural world is one country." So thought David Hilbert. He wrote Mathematics and the Imagination, and Nature and Mathematics, among other books.
Born in 1862 in Konigsberg, where Euler solved the problem of the Seven Bridges of Konigsberg, Hilbert died in 1943 in Gottingen, which had been the European centre of mathematics before the war. He contributed to geometry, invented "Hilbert space" in calculus, established a formalist school of mathematics, and expanded his work into mathematical physics.
At the Paris International Congress of Mathematicians in 1900, he gave a key lecture in which he assigned his fellow mathematicians "homework" for the new century. Among his twenty-three problems, several remain unsolved today. At the top of Hilbert's list is the Riemann Hypothesis, about which he once said, "If I were to awaken after a thousand years, my first question would be, 'Has the Reimann Hypothesis been proven?'"
In a blog post seven years ago, I recorded an anecdote about something strange Hilbert did. It's right here.