Poirot," I said. "I have been thinking." "An admirable exercise my friend. Continue it.
there is no fanatic like a religious fanatic.
the detective's highest talent lay in the gentle art of seeking favours under the guise of conferring them!
Evil is not something superhuman, it's something less than human.
What good is money if it can't buy happiness?
Imagination is a good servant, and a bad master.