Day 4: Knock knock knocking on... wood

Where did the euphemism "knock on wood" come from?

Motivation: My mom sent me an interesting forward the other day about where certain expressions came from and then today someone said "knock on wood"and it made me wanna know where the phrase came from.

Answer: 

I started this with a google search per my norm, using the phrase "origination of knock on wood."

Of the options, one was a source from the UK, so I figured that was a good place to start since the British are so much dang smarter than we are and we got our language from them.  (Well, the language I am willing to claim, not some of the slang from the youngsters today.)

Here is what I found on the origin of "knock on wood."  

The derivation may be the association that wood and trees have with good spirits in mythology, or with the Christian cross. It used to be considered good luck to tap trees to let the wood spirits within know you were there. Traditions of this sort still persist in Ireland.

The British version of the phrase - 'touch wood', predates the American 'knock on wood' and was itself preceded by a Latin version - 'absit omen', meaning 'far be that omen from us'. This dates from at least the early 17th century, when it is quoted by John Heywood in his collections of proverbs. It isn't clear when 'touch wood' began to be used as a token of good fortune but it must have been by 1850, when the academic correspondence magazine Notes and Queries published this:

There probably is some old English expression for averting evil, but it does not come to mind; "I touch wood," "Bar omen," "Bar ill-luck," seem clumsy.

'Knock on wood' is known from the early 20th century; for example, The Syracuse Herald, February 1905:

Neglecting to knock on wood may have been responsible for the weather's unseemly behaviour today.

Well, this didn't really answer my question... so back to the search.  So I went back to good ole wikipedia and came up with this:

• The early pagan tradition of "knocking on wood" was meant to drive out mischievous wood nymphs before they took an unfortunate suggestion and turned it into reality.

• In some countries, such as Spain, it is traditional literally to touch wood after an event occurs that is considered to bring bad luck, such as crossing paths with a black cat or walking under a ladder or noticing it's Friday the 13th. This is usually done when there's no salt at hand to spill over your shoulder, which is considered the "traditional" way of avoiding the bad luck caused by those situations.

• In Italy, "tocca ferro" (touch iron) is used, especially after seeing an undertaker or something related to death.

• In old English folklore, "knocking on wood" also referred to when people spoke of secrets – they went into the isolated woods to talk privately and "knocked" on the trees when they were talking to hide their communication from evil spirits who would be unable to hear when they knocked. Another version holds that the act of knocking was to perk up the spirits to make them work in the requester's favor. Yet another version holds that a sect of Monks who wore large wooden crosses around their necks would tap or "knock" on them to ward away evil.

• In Romania, there is also a superstition that one can avoid bad things aforementioned by literally knocking on wood ("a bate în lemn"). One of the possible reasons could be that there is a monastery practice to call people to pray by playing / knocking the simantron.

Rumination: I don't really like the wishy washy responses about this.  I would much prefer someone to tell me the exact person who started this saying and why they did it.  I guess I will accept the consensus about the wood nymphs/spirits in the tree, but why call it knock wood or touch wood?  Why not knock tree?  Ridiculous, I say.  I suppose history and I shall agree to disagree on this one.  Ridiculous.