Those who never think of money need a great deal of it.

I like living. I have sometimes been wildly, despairingly, acutely miserable, racked with sorrow, but through it all I still know quite certainly that just to be alive is a grand thing.

It is ridiculous to set a detective story in New York City. New York City is itself a detective story.

It is the brain, the little gray cells on which one must rely. One must seek the truth within--not without." ~ Poirot

Never do anything yourself that others can do for you.

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 think you're begging the question," said Haydock, "and I can see looming ahead one of those terrible exercises in probability where six men have white hats and six men have black hats and you have to work it out by mathematics how likely it is that the hats will get mixed up and in what proportion. If you start thinking about things like that, you would go round the bend. Let me assure you of that!"