The devil’s agents may be of flesh and blood, may they not?

I could not rest, Watson, I could not sit quiet in my chair, if I thought that such a man as Professor Moriarty were walking the streets of London unchallenged.

Data!data!data!" he cried impatiently. "I can't make bricks without clay.

I followed you.' I saw no one.' That is what you may expect to see when I follow you.

What can we know? What are we all? Poor silly half-brained things peering out at the infinite, with the aspirations of angels and the instinct of beasts.

I had ... come to an entirely erroneous conclusion, which shows, my dear Watson, how dangerous it always is to reason from insufficient data.

You see, but you do not observe.