Ouroboros

The earliest representation is three-and-a-half millennia ago, but the idea must be much older. Animals chasing their tails are commonplace; the idea of a snake chasing its tail, producing a perfect circle, must have occurred in more than one mind. As soon as you see it, or think it, it is instantly powerful - it doesnt need explaining - evidenced by the fact that it has been used and reused in so many ways across so many cultures. The religion around Tutankhamen, the Gnostics, the Norse gods, the Alchemists, the Hindus, the Aztecs, Occultists, Classical Antiquity and so on

My first encounter was in GCE Chemistry: August Kekulé, in 1865, publishing the molecular structure of benzene (a constituent of petroleum). He knew he was dealing with chains of carbon atoms, he knew the rules about joining them together chemically, but he couldn't make the maths work. By his own testemony, he gave up and took a nap; he dreamed of carbon chains dancing like snakes, then saw one of the snakes eating its own tail, woke with a start and knew he had the answer

Simple toys are the best. Each of the snakes segments, as arranged like this, is wider on the outside and narrow in the middle. They are strung together on tight elastic, through the centre, like beads. Segments can rotate against each other. Starting from this position, if each alternate segmen is rotated 180°, the snake becomes straight - with an infinite number of writhing positions between the two

One day, I'll try to tell him about the ouroboros, and Kekulé and benzene, and his great-grandfather's devotion to carbolic* soap, and ask him if he remembers the toy. I hope he'll humour me, as he has patiently humoured us today, doing our best to substitute for his Mum. If he is still listening (and why should he?), I'll tell him I find the ouroboros a dark and sinister symbol - a living thing that consumes itself, like our economic system, our politics, our species; that I hope he can one day help find some way to break the circle

*carbolic acid is a benzene ring with an oxygen atom added