How we dress is, as far as I can tell, the only inescapably public choice that we have. People don't need to know what you eat, people don't need to know who you have sex with. But there's no escaping what you wear and the fact that you've chosen it. Even if you insist that you don't care about fashion, that's your statement. It's really one realm of life where you are forced to make your own statement.
