You don’t have to believe me, but I would have known after one look at him, even if Fritz hadn’t told me. It’s mostly the eyes and the jaw. An FBI man spends so much time pretending he’s looking somewhere else that his eyes get confused; they’re never quite sure it’s okay to admit they’re focused on you. His jaw is even worse off. It is given to understand that it belongs to a man who is intrepid, daring, dauntless, cool, long-headed, quick-witted, and hard as nails, but it is cautioned that he is also modest, polite, reserved, patient, bland, and never to be noticed in a crowd. No jaw on earth could handle that order. The only question is how often it will twitch, and sideways or up and down.
— Rex Stout, The Final Deduction
(I really like the way Archie Goodwin describes people.)