Why do we cross our fingers to wish for luck?

Whether it’s making a wish over a birthday cake, waiting for lottery results, or opening an email following a job interview, it's pretty common to cross your fingers. It’s a way of communicating that we’re hoping luck swings in our favor and our wishes come true. Often, you don’t even need to physically cross your fingers; simply saying "Fingers crossed” is enough to get the message across. But the roots of this tradition go way back. In the Middle Ages, …