An expert is a person who avoids small error as he sweeps on to the grand¹ fallacy.

Benjamin Stolberg

Where facts are few, experts are many.

Donald R. Gannon

An expert is a person who has made all the mistakes that can be made in a very narrow field.

Niels Bohr (1885 - 1962)

My definition² of an expert in any field is a person who knows enough about what's really going on to be scared.

P. J. Plauger, Computer Language, March 1983

If the world should blow itself up, the last audible voice would be that of an expert saying it can't be done.

Peter Ustinov (1921 - 2004)

Always listen to experts. They'll tell you what can't be done and why. Then do it.

Robert Heinlein (1907 - 1988)

In the beginner's mind there are many possibilities. In the expert's mind there are few.

Shunryu Suzuki

Believe one who has proved it. Believe an expert.

Virgil (70 BC - 19 BC), Aeneid