"The friend noticed there above the entrance to the house, a horseshoe, which I don't know how it is here. In Europe it is a superstitious item preventing evil spirits to enter the house. So the friend asked Niels Bohr, but what you mean aren't you a scientist? Do you believe in this? Niels Bohr says, of course, I'm not crazy, I don't. So the friend asked him, why do you have it there? You know what Neils Bohr answered? He said, of course I don't believe in it, but I have it there because I was told that it works even if you don't believe in it." https://en.wikipedia.org/wiki/Niels_Bohr