One never quite allows for the moron in our midst.

I don't know. I don't know at all. And that's what's frightening the life out of me. To have no idea.

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

The best time to plan a book is while you're doing the dishes.

The human mind prefers to be spoon-fed with the thoughts of others, but deprived of such nourishment it will, reluctantly, begin to think for itself - and such thinking, remember, is original thinking and may have valuable results.

Any medical man who predicts exactly when a patient will die, or exactly how long he will live, is bound to make a fool of himself. The human factor is always incalculable. The weak have often unexpected powers of resistance, the strong sometimes succumb.

No, my friend, I am not drunk. I have just been to the dentist, and need not return for another six months! Is it not the most beautiful thought? --Poirot