Our memory is like that burning scrap of paper. We use it to light up the past. First of all our own, and then we ask old people to tell us what they remember. After that we look for letters written by people who are already dead. And in this way we light our way back. There are buildings that are just for storing old scraps of paper that people once wrote on – they are called archives. In them you can find letters written hundreds of years ago. In an archive, I once found a letter which just said: 'Dear Mummy, Dear Mummy, Yesterday we ate some lovely truffles, love from William.