The supernatural is only the natural of which the laws are not yet understood.

Hercule Poirot: I am an imbecile. I see only half of the picture. Miss Lemon: I don't even see that.

Time does not dispose of a question - it only presents it anew in a different guise.

Books are a habit-forming drug.

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.

marriage is an extraordinary thing - and I doubt if any outsider - even a child of the marriage - has the right to judge.

An appreciative listener is always stimulating.