Superstitions

Back in the past, people used to believe that the gods live in the tree trunks, so by touching them they get blessed.

Hope this amendment to this answer from another helps

Meaning

The phrase used by people who rap their knuckles on a piece of wood hoping to stave off bad luck. In the UK the phrase 'touch wood' is used - often jokingly by tapping one's head. The phrases are usually used when one is already experiencing some good fortune and hope that it will continue - e.g. "I've been winning on every race - touch wood".

Origin

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. See also - the darling buds of May.

The British version - touch wood, had an earlier Latin version used when touching wood - absit omen!, meaning 'far be that omen from us'. This dates from at least the early 17th century, when it is quoted by Heywood. It isn't clear when touch wood began to be used. It must have been well-known by 1849, when The Boy's Own Book published the rules of a children's game that derived from the phrase:

"This game 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."

Knock on wood - the American version, is known from the early 20th century. For example, The Indianapolis Star, September 1908:

As science now can explain these phenomena, superstition decreases. BTW, Ignorance is the mother of Superstitions, and Superstition is the mother of religions.. Falsely assuming a cause and effect. If you kick a goat on your way to school and get an F on your test, and it happens again, you might assume kicking goats is bad luck. But it's more likely that you weren't prepared for either of the tests.
Superstitions basically start with cause and effect, or at least a perception of it.

For example, you have a big soccer game, and just before the game you accidentally put your socks on inside out.

One of your team mates tells you it is bad luck to take them off and put them on right so you leave them and you have a fantastic game. Your team wins and you score a goal as part of that win. There is a germ of an idea that one thing effected the other.

The next game someone says something about your inside-out socks being lucky and sort of as a lark you put them on inside-out again. The game goes well, you score a goal and your team wins. The idea gets reinforced and it spreads a bit.

By the third game a couple of your buddies have decides to wear their socks inside-out too and the winning streak continues. Now the idea is really spreading and being reinforced.

Thereafter most of your team is wearing their socks inside-out and you are still winning games, until one day you think, "Heck, this is silly, I don't need to wear my socks inside-out to win." You don't wear the "lucky socks" and the law of averages catches up with you and the team looses.

Everyone notices you didn't turn your socks inside-out and the team lost. There it is, the perception of cause and effect and the "superstition" is born.

I'm betting the following game everybody is wearing their socks inside-out and if you should win, the superstition gets stronger.

• It has to do with the odds of it happening by random chance. It's like 1 in a billion which is almost the same as winning the lottery. So if you are statistically able to get bird poop on you, then you should also be able to win the lottery.

• Somebody came up with the idea that it's good luck because it's so disgusting that there must be something good about it.

This doesn't completely answer your question, but here's one example:

Nibelungen: Originated in Germany, Norway, and Denmark. Their element is earth. These Teutonic dwarf faeries live in a hidden subterranean crystal palace. They come to woodlands when the mood strikes, and this is where humans have seen them. They are tricksters and quite capricious, with a temperament most resembling that of the Irish Leprechaun. The Nibelungen's gold is guarded when they are not around by a dragon named Fafnir. Humans can obtain the gold only in the astral world; it will not travel back to the physical realm. Those who try to take it lose everything they have gained spiritually. These faeries are goldsmiths who make golden rings with magickal properties. They are best known for their rings of fertility which many a barren human has sought but failed to obtain. The Nibelungen seem to take great delight in the failings of humans who seek their magick and their world, and their merry laughter is often heard just as some hapless human falls, trips, or loses the prize they believe they have just won.