I believe, Messieurs, in loyalty---to one's friends and one's family and one's caste.

But I know human nature, my friend, and I tell you that, suddenly confronted with the possibility of being tried for murder, the most innocent person will lose his head and do the most absurd things.

You'll be glad too, when the end comes.

Poirot said placidly, “One does not, you know, employ merely the muscles. I do not need to bend and measure the footprints and pick up the cigarette ends and examine the bent blades of grass. It is enough for me to sit back in my chair and think. It is this – ” he tapped his egg-shaped head – “this, that functions!

Nobody knows what another person is thinking. They may imagine they do, but they are nearly always wrong.

Nurses - nurses, you'm all the same. Full of cheerfulness over other people's troubles.

The popular idea that a child forgets easily is not an accurate one. Many people go right through life in the grip of an idea which has been impressed on them in very tender years.