Why do we say "Touch wood"

[BockingBob]

Not meaning to bring bad luck on ourselves, we say "touch wood". Why?

[lajohn]

Bocking Bob you sound like a man. Men love to touch wood and it's the closest thing to them when they need to touch wood. Hope This Help!

[Abdulmajid]

Something to do with Christ on the wooden cross maybe??

But Americans say "knock on wood" which is knocking to scare the devil away according to my beloved.

[abstract]

To touch wood or knock on wood is a superstition action to avoid any evil consequences or bad luck, perhaps because of some recent action you�ve taken or untimely boasting about your good fortune. This gesture, can keep u safe from any harm and also be a charm to bring good luck.
The origin is unknown, though some writers have pointed to pre-Christian rituals involving the spirits of sacred trees such as the oak, ash, holly or hawthorn. Hence not iron or any other material objects. I also read about an old Irish belief that you should knock on wood to let the people know that you are thanking them for a bit of good luck. There�s also a belief that the knocking sound prevents the Devil from hearing your unwise comments. 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.
It wasn�t always wood that was lucky: in older days, iron was also thought to have magical properties, and to touch iron was an equivalent preventative against ill-fortune.
3 months ago

[lajohn]

abstract, well i never .... i'm shock you give a real answer. :-)

[bigmamma]

http://en.wikipedia.org/wiki/Touch_wood

[juandelacruz]

Steve Roud seems to have got the cart before the horse. Children often perpetuate old ideas by their conservatism. I think there's something in Graves' White Goddess, but it will take me a long time to find out; not a book you want to put down.