She didn't give George any too easy a time when she was alive. She was one of those semi-invalids – I believe she had really something wrong with her, but whatever it was she played it for all it was worth. She was capricious, exacting, unreasonable. She complained from morning to night. George was expected to wait on her, hand and foot and everything he did was always wrong and he got cursed for it. Most men, I'm fully convinced, would have hit her with a hatchet long ago.

Curious things, habits. People themselves never knew they had them. [Witness for the Prosecution, also published in The Hound of Death and Other Stories.]

There are some people who don't conform to the signals. An ordinary well-regulated locomotive slows down or pulls up when it sees the red light hoisted against it. Perhaps I was born color blind. When I see the red signal -- I can't help forging ahead. And in the end, you know, that spells disaster.

One knows so little. When one knows more it is too late.

Time is the best killer.

Never tell all you know—not even to the person you know best.

It's astonishing in this world how things don't turn out at all the way you expect them to.