It's customary to bang on a piece of wood quickly after discussing your own good fortune in order to prevent ill luck from happening. In more recent times, knocking has been substituted with only saying "knock on wood" (or "touch wood" in the UK). So, where did all of this originate?
Numerous pagans and other societies, from Ireland to India and other parts of the world, worshipped or mythologised trees until contemporary faiths arrived to ruin the festivities with their prohibitions against idolatry. Trees were consulted by some as oracles. Some people included them in their worship practices. Some people, such as the ancient Celts, believed that certain spirits and gods lived there.
Two links between banging on wood and these spirits are proposed by authors Stefan Bechtel and Deborah Aaronson in their books, The Good Luck Book and Luck: The Essential Guide.
The first theory on the origin of the term "knock on wood" is that it's a more contemporary version of the commotion that pagan Europeans created to drive bad spirits out of their homes or to keep them from learning about a person's good fortune and spoiling it.
Genesis of these tree worshippers
Another theory about the genesis of these tree worshippers is that some of them touched the trees with their hands to invoke the spirits or gods within them for favours. Later, when they had a string of good luck, they would praise the trees and touch them again to express their thanks to these otherworldly beings. It's possible that the religious ceremony evolved over ages into the superstitious knock that recognises and perpetuates good fortune.
"You are looking for defence against jealousy and resentment in either scenario," Bechtel wrote. "The wrath of the gods and the envy of evil spirits, who despise mortals with excessive arrogance and become especially irritated when they are the cause of your string of good luck and you show them no gratitude."
An additional option? that Tig Touch-Wood, a kid's game from the Victorian era, is where it all began. "Tig" is the person who represents "It," and once several trees have been selected as bases, "as long as the player is touching one of these authorised posts, Tig cannot touch him; his only chance is to catch him while flitting from one post to another," according to the book The Boy's Modern Playmate, published in 1891.
However, we assure anyone who may be superstitious that banging on wood is not a game for kids.