Where did the phrase and ritual "knock on wood" come from?

Answer 1

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. 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. 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.

The phrase itself is relatively modern, as the oldest citation for the British version of the phrase, touch wood, that I can find dates only from 1899. The American equivalent knock on wood is roughly contemporary, with my first example from 1905.

Answer 2

Little fuzzy on the details, but more than 1000 years ago, there was a pre-Christian nature worshipping group of people in England, (maybe northern Europe,) who believed good spirits lived in the trees. (Sorry, I don't remember if they were supposed to be elves, sprites, or what.)
When people needed their assistance or magical intervention of some sort, they thought they could call to these creatures by "knocking on the wood" of the trees.
In time, the act of knocking on the wood itself became a way to prevent bad luck, especially if used immediately after something potentially evil was said. (For example, "Hope he doesn't break his leg on those rollerblades." It was thought saying such words out loud would suggest the deed to evil spirts. Therefore, the speaker or a listener could prevent a potential accident by knocking on wood.)

Answer 3

I had a book on superstitions and it said the habit of knocking on wood came from a belief that there were spirits around you all the time and if you spoke of good fortune they would do what they could to mess it up. So in order to keep them from hearing you would knock loudly on the walls or the table to garble your speech. Thus knock on wood was a way to keep hoped for good luck from going bad.

Another tradition started at around the same time. It was believed that when you sneezed, you were expelling evil spirits from your body. If you were blessed quick enough, they wouldn't get back in. Hence, 'Achoo', "God Bless You" came to being.

Answer 4

once upon a time people somewhere believed that gods and souls lived in the trees and when they need help, they knocked the trees to call them out to help theirselves. that s what i know :)

Answer 5

my mommy