As to why knocking on wood, or even just touching wood, should confer positive outcomes, this stems back to the days when it was believed that spirits and deities lived in trees, and so a way of making contact. Somehow seems a more tactile expression of faith than just projecting your thoughts into the ether, maybe why christianity appropriated the superstition, with a slight sleight, with the idea of it stemming from the tapping the wooden beams of the cross of the crucifixion. Made from, thus, a dead tree, clearly giving a mixed message to the noviciates transferring over from paganism.
Be all that as it may, clearly the authors, Steve Cropper, guitarist of Booker T's MGs, and soul singer Eddie Floyd, thought it a potent totem for their 1966 chart hit, themselves then muddling matters up with its talk of thunder and lightning, forgetting what also "touches" wood in a thunderstorm. But their luck duly held, the song was a hit for Floyd, hitting number 28 on the Billboard chart, even better, 19, in the UK., and is now an acknowledged star in the Stax firmament.
But it didn't end there, with, to date, well over a hundred and twenty covers, spanning many styles and genres. Cropper himself reprised the song for an often overlooked album, Jammed' In, a trio effort between himself, Pops Staples and Albert King. I commend the album. Floyd also repeated himself, as part of the Blues Brothers circus of films and tours. (And, yes, I am sure that is also Cropper in that clip, his face often inconveniently masked by the neck of the bass guitar.)
David Bowie, on his exit from the Ziggy/Aladdin years, famously went funky, or his manifestation thereof, and David, Live, the live showcase of the Young Americans style, produced this version. The backing is all a bit loopier than the precision of original Muscle Shoals studio setting, the vocals all over the shop. Not originally included in the album, it was released as a single in Britain, hitting a very reasonable number 10 in the chart during 1974.
Which wasn't a patch on the 1978 version by Amii Stewart, made during some down time from musical touring duties in London's theatreland. This never more disco, syndrums to the fore, version became a worldwide smash, a number one in her American home territory. Whilst I was way too cool to ever then admit to liking either her version or disco music in general, I certainly recall her performance/outfit enlivening episodes of Top of the Pops. So huge was the song in the clubs that, when the film of Studio 54, 54, was made, in 1998, it was Stewart's showstopping performance that was reimagined as a set piece performance for the film, if pseudonymised. I have never worked out quite why a song with such subject matter should be so successful with the often largely gay clientele of such clubs, most of the surrounds being metallic. (Yeah, right.)
I would have liked to have found a really out there version to finish with; sadly this wasn't to be. So iconic is the song and so distinctive the riff that none seem to stray from the rigidity of the template. However, I confess to liking this version by James Taylor, as much for the smile on his face as he sings it, acknowledging just how great a song it is.
Knock, knock.....