不识卢山真面目 只缘身在此山中

A (small) joke told in the hallways of MIT ran, "Do you know Hilbert? No? Then what are you doing in his space?" (S. A. Vaughn, pers. comm., Jul. 31, 2005).

I am an idiot running madly inside Hilbert space n till now still dont ustd what is Hilbert space all abt.

:-(