„“This affair must all be unravelled from within.” He tapped his forehead. “These little grey cells. It is ‘up to them’ — as you say over here.”“

— Agatha Christie
„You should employ your little grey cells“
— Agatha Christie
„If you set yourself to it, you can live the same life, rich or poor. You can keep on with your books and your ideas. You just got to say to yourself, "I'm a free man in here" - he tapped his forehead - "and you're all right.“
— George Orwell
„It is the brain, the little gray cells on which one must rely. One must seek the truth within--not without." ~ Poirot“
— Agatha Christie
„The little waiter's eyebrows wandered about his forehead in confusion.“
— Douglas Adams
„You have an excellent heart, my friend — but your grey cells are in a deplorable condition.“
— Agatha Christie