Here is a famous story. I don't know if it is true.
An American scientist once visited the offices of the great Nobel Prize-winning physicist, Neils Bohr, in Copenhagen, and was amazed to find a horseshoe was nailed to the wall over his desk.
The American said with a nervous laugh, "Surely you don't believe that horseshoe will bring you good luck, do you, Professor Bohr?"
Bohr chuckled. "I believe no such thing, my good friend. Not at all. I am scarcely likely to believe in such foolish nonsense. However, I am told that a horseshoe will bring you good luck whether you believe in it or not! How can one argue with such logic?"