One Knows So Little. When

Hercule Poirot: I Am An Imbecile. I See Only Half Of The Picture. Miss Lemon: I Don't Even See That.

You'll Be Glad Too, When The End Comes.

Oh, No, I'm Not Brave. When A Thing Is Certain, There's Nothing To Be Brave About. All You Can Do Is To Find Your Consolation.

The Impossible Could Not Have Happened, Therefore The Impossible Must Be Possible In Spite Of Appearances.

One Must Make One's Own Mistakes