It then dawned on me that I must be a bit daft - a sensible, grown woman like me (ok, you can stop laughing now), muttering away to herself, dodging the cracks in the pavement, avoiding walking under ladders, chucking salt over her left shoulder (or should it be the right shoulder?) at every available opportunity and saluting magpies in broad daylight must look a right sight.
So why do we do it? We cross our fingers for good luck and then assume, when the good fortune is bestowed upon us, that it was solely because we crossed our fingers - nothing to do with coincidence at all, is it...? It's the same as when we throw a ball or take a shot in a game of pool; after the shot has been taken we swerve our body to try and encourage the ball to take the desired course, congratulating ourselves when it meets its target.
So are superstitions a way of positive thinking? If we cancel as much negativity out of our lives as possible then there is more room for fortuity. If that is so then I'm all for not passing someone on the stairs (there isn't actually room for that on our stairs so I'm safe there), not opening umbrellas indoors and running down the street so that a black cat can walk across my path and hope that people won't think that I'm a little strange. Touch wood.