Pea-soupers and opium dens

So: does Moriarty exist, or not? Well no, not really, and not just in the literal sense of being a fictional character. He’s hardly even that. We have no evidence beyond Sherlock Holmes’s word, and if you look at Holmes’s behaviour in ‘The Final Problem’ you can see an almost classic case of paranoia — brought on, no doubt, by a heavy cocaine binge.