A Theory Is Not Complete Until You Can Explain It To the Person in the Street

David Hilbert? Mary Winston Newson? Adolphe Quetelet? Joseph Diez Gergonne? Michel Chasles? William Spottiswoode? Henry John Stephen Smith? G. Carey Foster? Alphonse Rebière? Anonymous? Dear Quote Investigator: In 1900 the influential German mathematician David Hilbert addressed the “International Congress of Mathematicians” held in Paris. He presented a collection of unsolved problems which has had an …