I have a print – you can buy them at the Victoria and Albert Museum – of a photograph of the village street of Thetford, taken in 1868, in which William Smith is not. The street is empty. There is a grocer’s shop and a blacksmith’s and a stationary cart and a great spreading tree, but not a single human figure. In fact William Smith – or someone, or several people, dogs too, geese, a man on a horse – passed beneath the tree, went into the grocer’s shop, loitered for a moment talking to a friend while the photograph was taken but he is invisible, all of them are invisible. The exposure of the photograph – sixty minutes – was so long that William Smith and everyone else passed through it and away leaving no trace. Not even so much of a mark as those primordial worms that passed through the Cambrian mud of northern Scotland and left the empty tube of their passage in the rock.

I like that. I like that very much. A neat image for the relation of man to the physical world. Gone, passed through and away. Suppose though that William Smith – or whoever did walk down that street that morning – had in his progress moved the cart from point A to point B. What would we see then? A smudge? Two carts? Or suppose he had cut down the tree? Tampering with the physical world is what we do supremely well – in the end, perhaps, we shall achieve it definitively. Finis. And history will indeed come to an end.

– Penelope Lively, Moon Tiger (1987), p. 13