Why do we touch or knock on wood? Most of us also have the feeling that if things are going well, too well, something is wrong or is bound to go wrong, and it is to guard against this change in fortune, that we use the phrase ‘touch wood’. Today ‘touch wood’ is a Standard English idiomatic expression, and its American equivalent is ‘Knock on wood’.
Although it is certain that the belief is connected to a religious belief of superstition, its exact origin is uncertain and various theories abound, although most of them revolve around either the power of trees to drive away bad luck or as a sign of respect to the Gods who are said to have blessed the trees with these powers. Thus wood has since ancient times been associated with the Gods, magic, good fortune and even safety.
Touchwood was also the name of Catweazle's familar in the TV series Catweazle.
Catweazle featured Geoffrey Bayldon as the title character, an eccentric, incompetent, dishevelled and smelly (but lovable) old 11th Century wizard who accidentally travels through time to the year 1970 and befriends a young red-headed boy, nicknamed Carrot (Robin Davies), who spends most of the rest of the series attempting to hide Catweazle from his father and farmhand Sam. Meanwhile Catweazle searches for a way to return to his own time whilst hiding out in 'Castle Saburac', a disused water tower, with his 'Familiar', a toad called Touchwood.
Catweazle mistakes all modern technology for powerful magic, particularly 'electrickery' (electricity) and the 'telling bone' (telephone).