Never tell all you know—not even to the person you know best.

a lot of trouble has been caused by memoirs. Indiscreet revelations, that sort of thing. People who have been close as an oyster all their lives seem positively to relish causing trouble when they themselves shall be comfortably dead.

If one sticks too rigidly to one's principles, one would hardly see anybody.

there is evil everywhere under the sun.

All I needed was a steady table and a typewriter...a marble-topped bedroom washstand table made a good place; the dining-room table between meals was also suitable.

You've a pretty good nerve," said Ratchett. "Will twenty thousand dollars tempt you?" It will not." If you're holding out for more, you won't get it. I know what a thing's worth to me." I, also M. Ratchett." What's wrong with my proposition?" Poirot rose. "If you will forgive me for being personal - I do not like your face, M. Ratchett," he said.

Use that fluff of yours you call a brain.