If you confront anyone who has lied with the truth, they usually admit it — often out of sheer surprise. It is only necessary to guess right to produ… - Agatha Christie

"He played the part of the devil too successfully. But he was not the devil. Au fond, he was a stupid man. And so - he died."
"Because he was stupid?"
"It is the sin that is never forgiven and always punished, madame."

One cannot be interested in crime without being interested in psychology. It is not the mere act of killing, it is what lies behind it that appeals to the expert.

There is always a brave new world,” said Poirot, “but only, you know, for very special people. The lucky ones. The ones who carry the making of that world within themselves.