Why do people "knock on wood" after making a hopeful statement?

Question

I had heard it has something to do with Tree Spirits and Scandinavian culture. You always hear of people "knocking on wood" but don't know why.

Answer 1

Knocking on wood, and the spoken expression "knock on wood" or "touch wood" are used as a charm to bring good luck or to avoid "tempting fate" after making some boast or speaking of one's own death.

It is commonly thought that knocking on wood has been a superstitious action to ward off evil throughout history. Some believe it has to do with knocking on the wooden cross. Another explanation for this practice is the pagan belief that spirits (dryads) lived in trees. By knocking on the wood of a tree while making some sort of a bold statement, the speaker could prevent the spirit from hearing him and stop the spirit from interfering.

Answer 2

It wakes the spirits in the wood. Works better with a living tree. Knocking on your desk won't wake up anyone except your cube mate.

Answer 3

If I recall correctly, it was to wake up the spirits in the wood; I think to drive the bad spirits out with the knocking, or waking up the good ones.

Answer 4

Knocking on wood is supposed to ward away bad luck.

Here is a great book to read it has every superstition and its origin.

Dictionary of Superstitions
By David Pickering
Published by Cassell.

Answer 5

My lover write of Security Beliefs, one begin with knock on wood, he say it come from invoking dryads, nymphs spirits of trees. Dryads Greek not Scandanavian.

Answer 6

to wake up the gods so he hears your wish and does your bidding it is an old pagan idea

Answer 7

IDK...cuz they are a bunch of retards...
they look so dumb doing it too...I just laugh!

Answer 8

Because they are superstitious twits.

Answer 9

i don't know, but i do it ALL the time, lol