This superstition can be traced to the early 1800s, with some people believing it invokes the wood of the crucifix for protection.
The real origin seems to be a children’s game from the early 1800s called “Tig-touch-wood”. Children playing tag were “safe” when they touched wood. Touching wood for luck became knocking on wood for luck in the U.S. and Germany.
(Cross-posted at DDBBG.)
Reference: Most of the material from this post was found in Steve Roud's The Penguin guide to the superstitions of Britain and Ireland.
Posted by Jennifer at April 7, 2008 12:47 PM | TrackBack