Five years ago this week I published my first blog posting here. Since then 850 posts of varying length and significance have appeared. Wood is the traditional gift for a five-year anniversary, which made me think of the phrase "knock on wood." You know, when you tap your knuckles on wood to ward off bad luck or to continue good fortune, e.g., "I haven't missed a week of blog-posting yet, knock on wood." The U.K. variation is "touch wood." Turns out the saying may have Irish origins. I found the following explanation about the phrase on the website WorldWideWords.org: 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 symbolizes the timber of the cross, but this may be a Christianisation of an older ritual... The phrases are relatively modern with "touch wood" first appearing in print in about 1899 and "knock on wood" a few years later. Here's to five more years, knock on wood.