Niels [Bohr] closed the conversation with one of those stories he liked to tell on such occasions: "One of our neighbors in Tisvilde once fixed a horseshoe over the door to his house. When a common friend asked him, `But are you really superstitious? Do you honestly believe that this horseshoe will bring you luck?' he replied, `Of course not; but they say it works even if you don't believe in it.'"Just like locality and causality.