touching wood and knocking wood

[Richard Gage]

According to Quinion, "knock on wood" is merely an Americanization of
"touch wood."
<  http://www.quinion.com/words/qa/qa-tou1.htm >
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"Touch wood" appears in the OED, but I could find no mention of "knock^
on wood."

[from the OED]:
TOUCH, v.

29. In to touch wood.    a. In a children's game: see quots. 1849,
1888.    b. In folk-lore, or quasi-superstitious use: To touch wood as a
charm to avert apprehended misfortune, esp. that apt to follow untimely
boasting or self-gratulation: cf. L. absit omen! (OMEN n., quot. 1637).

1849 Boy's Own Bk. 37
This..game [TOUCH n. 1g] is sometimes called 'Touch-iron' or
'Touch-wood'; in these cases the players are safe only while they touch
iron or wood, as may be previously agreed. They are liable to be touched
only when running from one piece of wood or iron to another.

1888 Berksh. Gloss., Touch 'ood.
Boys have games called 'touch 'ood' and 'touch-iron', where anyone not
touching either of the substances named is liable to be caught by the
one standing out and has to stand out accordingly.

1908 Westm. Gaz. 30 Dec. 2/3
On the next occasion when we read of Christmas with spring weather or of
the changing seasons we shall 'touch wood'.
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KNOCKING ON WOOD
Some theories about origin: <
http://www.plateaupress.com.au/wfw/knock.htm >

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[A notable use of the expression "knocking on wood" in the lyrics for
John Prine's "Dear Abby]:
< http://www.jpshrine.org/lyrics/songs/jpdearabby.html >

Dear Abby
©John Prine

     Dear Abby, Dear Abby ...
     My feet are too long
     My hair's falling out and my rights are all wrong
     My friends they all tell me that I've no friends at all
     Won't you write me a letter, Won't you give me a call
          Signed Bewildered

     Bewildered, Bewildered...

     Chorus:
     You have no complaint
     You are what your are and you ain't what you ain't
     So listen up Buster, and listen up good
     Stop wishing for bad luck and knocking on wood

     Dear Abby, Dear Abby...
     My fountain pen leaks
     My wife hollers at me and my kids are all freaks
     Every side I get up on is the wrong side of bed
     If it weren't so expensive I'd wish I were dead
       Signed Unhappy

     Unhappy, Unhappy...

     Repeat Chorus

     Dear Abby, Dear Abby...
     You won't believe this
     But my stomach makes noises whenever I kiss
     My girlfriend tells me It's all in my head
     But my stomach tells me to write you instead
       Signed Noise-maker

     Noise-maker, Noise-maker

     Repeat Chorus

     Dear Abby, Dear Abby...
     Well I never thought
     That me and my girlfriend would ever get caught
     We were sitting in the back seat just shooting the breeze
     With her hair up in curlers and her pants to her knees
        Signed Just Married

     Just Married, Just Married...

     Repeat Chorus