The adventure of the speckled band
"Well, you can find lots of those whips. But I don't know why it should have that knot."
"Yes, you do not find the knot very often. Oh dear! The world is a bad place. And when a clever man becomes a criminal, that is worst of all. I think that I have seen enough now, Miss Stoner. Let's have a walk on the lawn."
My friend's face was very serious. He looked very angry. We walked up and down the lawn. We could see that Sherlock Holmes was thinking hard about something, and we did not want to interrupt him until he finished.