If you stand up to people, they'll respect you for it. I had an e-mail from a Cambridge University American law student, and he said, 'You are an evil f------ man,' so I called him up - he put his telephone number on it - and I said, 'I'm going to call the police if I have any more messages like this from you. This is an abusive, threatening letter.' And he invited me to give a lecture. I couldn't do it, but I would have done it if I'd had the time.