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!
Agatha ChristieThere is nothing so dangerous for anyone who has something to hide as conversation!... A human being, Hastings, cannot resist theopportunity to reveal himself and express his personality which conversation gives him. Every time he will give himself away.
Agatha Christie