Believing in things we don't understand is a common theme in human history.
But while it's fine to belive in God and the afterlife, despite both being beyond human comprehension, believing that a cracked mirror brings seven years' bad luck is sneered at.
The word superstition is often used as a pejorative term, as if saluting magpies denotes a feeble mind.
Those keen to dismiss religious beliefs can be heard to dismiss them by applying the epithet 'superstition'.
Clearly superstition is an irrational belief. But as Steve Roud, an expert on superstitions (how does one become one of those?), points out, not all irrational beliefs are dismissed as superstition.
'One of the key characteristics of superstition is a belief in the existence of luck, as a real force in life, and that luck can be predicted by signs, and can be controlled or influenced by particular actions or words,' he writes in his Penguin pocket guide on the subject.
He calls superstitions 'unofficial knowledge, in that they run counter to the official teachings of religion, school, science and government'.
The most commonly observed superstitions seem all to come from the distant past.
Is this perhaps why they persist in the 21st century? Because we yearn for a life that isn't ruled by harsh empirical scientific facts?
Certainly, one finds it difficult to imagine the modern world spawning superstitions comparable to plucking petals to discern whether she loves you.
A mobile in the hand is worth two in the pocket. Spilled cappuccino on your keyboard, seven years' bad luck.
The Welsh, according to Mr Roud, have long had their own set of signs and omens to augur good and bad luck. He quotes a source from 1909 which says St David was particularly keen for his people to know if they were about to die. …