I told my daughter that I would knock on wood about something, and she said, "Mom, you can't do that. Knock on wood is a Christian saying, meaning to knock on the cross. We're Jewish!" Well, I had not heard that and did a little searching. According to World Wide Words, that is probably not true, though the origin is not known:
"The origin is quite unknown, though some writers have pointed to pre-Christian rituals involving the spirits of sacred trees such as the oak, ash, holly or hawthorn. There is, I'm told, an old Irish belief that you should knock on wood to let the little people know that you are thanking them for a bit of good luck. Others have sought a meaning in which the wood symbolises the timber of the cross, but this may be a Christianisation of an older ritual."
Does anyone know more about this phrase? What other superstitious phrases are there?

I've long thought that knocking on wood was analogous to beating my head against a wall. I do believe the term dates to pre-Christian times, and, like so many other superstitions, was appropriated by the Christians.

If you happened to catch Bill Moyers' TV show last night, one of his guests, Gregory Nava, was discussing how in Guatamala, Catholicism is only a slim veneer over the pre-Columbian mythos of the people.



As for other superstitious sayings, "Step on a crack; break your mother's back." Now, where'd THAT one come from

Other superstitions:

Bad luck if a black cat crosses your path!

Well, my cat, Lucky, the blackest cat you have ever seen, has changed my thoughts on that one!

Aside: There was a song a few years ago called "I Feel Lucky" by Mary-Chapin Carpenter. Every time the song would come on the radio, one of us would grab the cat and dance around the kitchen with him! He still cowers when he hears it come on! (Yes, we are a sick family! )

According to "Origin of Phrases"
http://members.aol.com/MorelandC/HaveOrigins.htm

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Knock on wood

Meaning: If good luck is willing.

Example: I am sure that your tax returns will not be audited, knock on wood.

Origin: 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. There were also several Holy Foreskins around at the time ..but that was a different story!
Thanks to Zebulun

Alternatively,

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.

Thanks to Cynthia Blackledge

Alternatively,

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.

Thanks to Coach Alan and Fluke
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Chuck Moreland runs this site. He requests that people submit phrase origins and then he posts them on his site. He has a list of phrases whose origins are unknown (to him, at least), one of which is "nine ways to Sunday". I believe this was discussed earlier on this board. If anyone has any idea of the origin of this phrase, please send it to Chuck (morelandc@aol.com).

Tinman

"Word for Word" (http://www.plateaupress.com.au/wfw/knock.htm) also has theories about the origin of about knock on wood. Morgan, one of those is a Jewish origin.

Knock on wood

Kyrja: What is the origin of "knock on wood"?

Mel Goodman: In the middle ages Christian pilgrims would carry a small wooden cross with then which they would touch for luck. Later on any wood which was touched would represent the wood of the cross.

Bettencourt: From Morris Dict. of Word and Phrase Origins, several theories

In child's game of tag the one able to touch a tree is free from capture.

Biblical...wood symbolizes the cross... If you have made an exaggerated boast you are forgive if you turn your thoughts to the cross.

Goes far back into ancient times (with) spirits thought to live in trees. If danger threatens, rap a tree to call the good spirit within.

Irish belief that knocking on wood let the leprechans know that you are thankful for good luck.

Jewish version: Spanish Inquisition under Torquemada (c1490). Jews in flight knocked on synagogues ddoors with code for entry. Thus lives were saved by knocking on wood. Hence, good luck.

Take your pick, but be sure to knock on wood so you pick the right one.

Tinman