“That, my friend, I do not tell.' 'Nonsense. Why not?' Poirot's eyes twinkled. 'Because, mon cher, you are the same old Hastings. You have still the speaking countenance. I do not wish, you see, that you should sit staring at X with your mouth hanging open, your face saying plainly: "This -- this that I am looking at -- is a murderer." ' 'You might give me credit for a little dissimulation at need.' 'When you try to dissimulate, it is worse. No, no, mon ami, we must be very incognito you and I. Then, when we pounce, we pounce.' -” HumourBlindnessDissimulationPoirot S HumourSpeaking Countenance Book:Curtain Source: Curtain