Anyone know where the phrase “knock on wood” originated? This came up at work the other day and no one knew the answer.
The story I’ve heard is that you would knock on a tree to wake up the tree spirit, or dryad, that lived there. You could then ask the spirit to help you out of whatever difficulty you happened to find yourself in. My feeling now though is if the dryad wakes up to find its tree converted into a veneer and particle board computer desk, it’s going to be so royally pissed off that it is more likely to wreak its vengeance on you than help you out. Let sleeping nymphs lie, I always say.
I have heard that it has to do with that during the Middle Ages people would have pieces of the “True Cross” of Chirst. They would knock on this to evoke his help or good luck. I have also heard the tree explanation posted by Greg.
Signify that piece of protrusion above your neck that you remind yourself that you should have used before arriving at the predicament with which you find yourself needing to knock on? No?
There is a nautical derivation of this phrase as well. Sailors, when far out at sea and talking of making it back home or surviving a storm would utter, “Touch wood”. This action was based upon touching some form of land based material (trees grow on land) so as to ensure their safe return to port.
Remember, being superstitious is bad luck.
see this threads on the same subject
http://boards.straightdope.com/sdmb/showthread.php?threadid=37978