As I'm a writer, I'll begin with a story. It's not, I'm sorry to say, one of my own – I wish it were – but it is very philosophical. It's by the great blind Argentinian, Jorge Luis Borges, and it's called ‘Funes the Memorious’. Somewhere in a marshy province of Uruguay, Borges comes across a young man called Funes who has gone into an extraordinary mental state after a crippling fall from a horse. He is quite unable to forget anything that has ever happened to him in his physical or mental life. He ‘not only remembered every leaf on every tree of every wood, but even every one of the times he had perceived or imagined it’ – and with exceptional vividness. In an attempt to manage this colossal burden, Funes thinks about classifying and reducing his memories to some practical order. But ‘two considerations dissuaded him: the thought that the task was interminable, and the thought that it was useless. He knew that at the hour of his death he would scarcely have finished classifying even all the memories of his childhood.’