Any medical man who predicts exactly when a patient will die, or exactly how long he will live, is bound to make a fool of himself. The human factor is always incalculable. The weak have often unexpected powers of resistance, the strong sometimes succumb.

Evil is not any superhuman, but it is HUMAN.

Evil is not something superhuman, it's something less than human.

It's a mystery to me how anyone ever gets any nourishment in this place. They must eat their meals standing up by the window so as to be sure of not missing anything.

There are questions that you don't ask because you're afraid of the answers to them.

Vous eprouves trop d'emotion, Hastings, It affects your hands and your wits. Is that a way to fold a coat? And regard what you have done to my pyjamas. If the hairwash breaks what will befall them?' 'Good heavens, Poirot,' I cried, 'this is a matter of life and death. What does it matter what happens to our clothes?' 'You have no sense of proportion Hastings. We cannot catch a train earlier than the time that it leaves, and to ruin one's clothes will not be the least helpful in preventing a murder.

I admit," I said, "that a second murder in a book often cheers things up." - Hastings