One must always proceed with method. I made an error of judgment asking you that question. Toeach man his own knowledge. You could tell me the details of the patient's physical appearance- nothing there would escape you. If I wanted information about the papers on the desk, Mr. Raymond would have noticed anything there was to see. To find out about the fire, I must ask the man whose business is to observe such things. - Detective Hercule Poirot to Doctor Sheppard
Agatha Christie, The Murder of Roger Ackroyd
mystery