An expert is someone who knows some of the worst mistakes that can be made in his subject and who manages to avoid them.

-Heisenberg,Werner
  Der Teil und das Ganze, translated by A  J Pomerans as Physics and Beyond (1971).

The poker player learns that sometimes both science and common sense are wrong; that the bumblebee can fly; that, perhaps, one should never trust an expert; that there are more things in heaven and earth than are dreamt of by those with an academic bent.

-Mamet, David Alan
  Writing in Restaurants,'Things I Have Learned Playing Poker On The Hill'.

There is much to learn from architecture before it became an expert's art.

-Rudofsky, Bernard
  Architecture without Architects.