As I was heading for the chemist the other day, a very large, wild-looking man paced outside, agitated, mumbling, grubby. He came in while I was waiting to be served, walked distractedly up and down for a bit and then stood still beside me and loomed. I turned to look at him. 'I'm not drunk,' he said to me, 'I'm mental.' Actually, that was what I supposed he was. Street drunk looks different from street mad. I understood the distinction as well as he wanted me to. I once lived in a flat full of dopers with a junkie who insisted: 'You lot just take drugs, but I'm an addict.' He meant both that he was more serious then we were, and that he was under the doctor. It's probably the case that being an alcoholic is as much of a condition as being 'mental', but there's a kind of respectability or responsibility hierarchy involved.