A mathematical theory is not to be considered complete until you have made it so clear that you can explain it to the first man whom you meet on the street.

(This is not Mathematics. As a result he demonstrated Hilbert's basis theorem showing the existence of a finite set of generators for the invariants of quantics in any number of variables but in an abstract form. "

By the time Hilbert died in 1943 the Nazis had nearly completely restaffed the university in as much as many of the former faculty had either been Jewish or married to Jews.

David Hilbert ForMemRS (German: [ˈdaːvɪt ˈhɪlbɐt]; January 23 1862 – February 14 1943) was a German mathematician. He also formulated the theory of Hilbert spaces one of the foundations of functional analysis. Hilbert and his students contributed significantly to establishing rigor and developed important tools used in modern mathematical physics.