United by analogy

Douglas Hofstadter, on this week's Radiolab.

Look, we have one photograph of Frederic Chopin. One photograph. What did Frederic Chopin really look like? What was his smile like? You know, you look at a photograph of Chopin and you say "Oh, this is what Chopin looked like." Well, no, Chopin looked like many things. Even the very day that that photograph was taken, he had thousands of different expressions on his face. But then what about a year earlier? Or ten years earliers? I mean, knowing Chopin is a very complex thing; it's not one thing, it's millions of different things that are united by analogy into something that we refer to as one thing.