“I don’t know,” he said. “Miller, the man who’s on this case, is a smart chap. You may be very sure he won’t overlook a footprint, or a cigar-ash, or a crumb even. He’s got eyes that see everything.”

“So, mon ami ,” said Poirot, “has the London sparrow. But all the same, I should not ask the little brown bird to solve the problem of Mr. Davenheim.”

“Come now, monsieur, you’re not going to run down the value of details as clues?”

“By no means. These things are all good in their way. The danger is they may assume undue importance. Most details are insignificant; one or two are vital. It is the brain, the little grey cells”⁠—he tapped his forehead⁠—“on which one must rely. The senses mislead. One must seek the truth within⁠—not without.”