NegativeMode's Foray Into Etymology

I have a mild fascination with word and phrases and their history, i.e., etymology. As such, I've decided to make etymology a minor theme on NegativeMode (please be aware that I may totally forget about this and you may never see it again. Such is life.). If you have no interest in this, well, I suppose you could skip reading this post, but really, that would just prove to us all that you're a dolt . . . so read on.

I don't consider myself a very superstitious person, but something that I find myself doing all the time is "knocking on wood". I have a theory that you can only knock on wood once a day, or else the second or third knock will override the previous knock, thereby ruining your previous knocking and making the process all for naught. That's my own theory though, and although I can point to no evidence that backs it up, it just seems right to me. Anyway, I was curious as to why I "knock on wood" when I want "good luck to be willing", so I did some research. Apparently, no one has a good reason as to why we knock on wood, but here are the three most common explainations for this strange superstition. . . .

1) One theory is that it originated in the middle ages when there were in circulation, pieces of the Holy Rood or Cross on which Jesus was crucified. To touch one of these was supposed to bring good luck hence touch wood for good luck.

2) The Druids, who worshipped trees, especially Oaks, wore a piece of Oak around their neck to ward off evil spirits. Hence touch wood for good luck. (I think that this is the correct one, although again, I have nothing to back that up. It just makes the most sense to me.)

3) You knock on wood because of those wily Wood Sprites. In medieval times, people believed in mischievous creatures known as sprites. Sprites are actually spirits or ghosts who were reputed to enjoy causing trouble and wreaking havoc in the lives of the living. Among the most mischievous were wood sprites. If you were to mention something good, the wood sprites would try to foul it up. The thought was that if you knocked on the wood when you said these things, the wood sprites would not be able to hear you because of the knocking sound. Hence they would leave you alone. (On second thought, this makes sense to me too. Really, I just find the Jesus one to be poppycock, but maybe that's because I'm a Jew. (I also sort of believe in wood sprites, gnomes (especially underpants gnomes), and leprechauns.))

Anyway, that's the disputed history of why we knock on wood. I have no idea if any of you find this interesting other than me (please let me know if you do, as I have some other interesting phrase origins ready and waiting for your perusal). Hopefully, you were all quite intrigued. Knock on wood. . . .