In my experience, people who go about looking for trouble usually find it.

Who are you? You don't belong to the police?' 'I am better than the police,' said Poirot. He said it without conscious arrogance. It was, to him, a simple statement of fact.

Downstairs in the lounge, by the third pillar from the left, there sits an old lady with a sweet, placid, spinsterish face and a mind that has plumbed the depths of human iniquity and taken it all as in the day's work....where crime is concerned, she's the goods.

But surely for everything you love you have to pay some price.

If you place your head in a lion's mouth, then you cannot complain one day if he happens to bite it off.

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

I learned ... that one can never go back, that one should not ever try to go back - that the essence of life is going forward. Life is really a one way street, isn't it?