Chances are you’ve knocked on wood in the past month. But, really, why? Here’s one origin story:

Knocking on wood is thought to come from the folklore of the ancient Indo-Europeans, or possibly people who predated them, who believed that trees were home to various spirits.

Touching a tree would invoke the protection or blessing of the spirit within.

Somehow, this tradition has survived long after belief in these spirits had faded away.

To learn more about superstitions, watch this TED-Ed Lesson: Where do superstitions come from?

Art credit: TED-Ed/@jefflebars

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Tags: GIFs, Knock on Wood, Superstitions