A visitor to Niels Bohr's country cottage, noticing a...

A visitor to Niels Bohr's country cottage, noticing a horseshoe hanging on the wall, teasing the eminent scientist about this ancient superstition. "Can it be true that you, of all people, believe it will bring you luck?' 'Of course not,' replied Bohr, 'but I understand it brings you luck whether you believe it or not.'