In my study hangs a fine old horse shoe, which I found in an abandoned Western ghost town. I don't believe in superstitions, but it is supposed to work even for a nonbeliever2. It hasn't so far.

2 For historians: This fact was conveyed to me in 1941 by I. Bernard Cohen, the historian of science at Harvard University. I passed it on to Niels Bohr in 1954 when he visited Brookhaven. It is now known as "Bohr's story". W. Heisenberg, in his book Der Teil und das Ganze, incorrectly has Bohr telling it already in 1927.

Bias (Physical Review Letters 25 (1970) 419-20)