My mother and I were talking about the origin of the habit of knocking on wood. With the internet close at hand, I couldn’t leave it at mere contemplation and conversation. Straight to google and that lead us to this yahoo answer. It makes me think about all the time spent in card catalogs, microfilm, encylopedia’s in my school days researching and how know the kids just “google” it and their research will appear. Ah, the new generation.
Greeks worshipped the oak as it was sacred to Zeus, Celts believed in tree spirits, and both believed touching sacred trees would bring good fortune. Irish lore holds that “touching wood” is a way to thank the leprechauns for a bit of luck. Pagans also held similar beliefs of protective tree spirits. Chinese and Koreans thought the spirits of mothers who died in childbirth remained in nearby trees.
Another explanation points to the wooden Christian cross as the origin of “good luck,” although this is likely a Christian adaptation of earlier pagan practices.
A Jewish version traces the origin to the Spanish Inquisition of the 15th century. At the time, persecuted Jews fled to synagogues built of wood, and they devised a coded knock to gain admission. Since this practice spared countless lives, it became common to “knock on wood” for good luck.