A weak man in a corner is more dangerous than a strong man.

Now I am old-fashioned. A woman, I consider, should be womanly. I have no patience with the modern neurotic girl who jazzes from morning to night, smokes like a chimney, and uses language which would make a billingsgate fishwoman blush!

It is the quietest and meekest people who are often capable of the most sudden and unexpected violences for the reason that when their control does snap, it goes entirely. (Hercule Poirot)

When you find that people are not telling you the truth---look out!

It's very inconvenient to be loved. Nearly everyone has found that out, sooner or later. The fewer people who love you the less you will have to suffer.

Curious things, habits. People themselves never knew they had them. [Witness for the Prosecution, also published in The Hound of Death and Other Stories.]

In old days the public didn't really mind much about accuracy, but nowadays readers take it upon themselves to write to authors on every possible occasion, pointing out flaws.