THE MISTAKE OF THE MACHINE
"You always forget," observed his companion, "that the reliable machine always has to be worked by an unreliable machine."
"Why, what do you mean?" asked the detective.
"I mean Man," said Father Brown, "the most unreliable machine I know of. I don't want to be rude; and I don't think you will consider Man to be an offensive or inaccurate description of yourself. You say you observed his manner; but how do you know you observed it right? You say the words have to come in a natural way; but how do you know that you did it naturally? How do you know, if you come to that, that he did not observe your manner? Who is to prove that you were not tremendously agitated? There was no machine tied on to your pulse."
"I tell you," cried the American in the utmost excitement, "I was as cool as a cucumber."
"Criminals also can be as cool as cucumbers," said Brown with a smile. "And almost as cool as you."
"Well, this one wasn't," said Usher, throwing the papers about. "Oh, you make me tired!"
"I'm sorry," said the other. "I only point out what seems a reasonable possibility. If you could tell by his manner when the word that might hang him had come, why shouldn't he tell from your manner that the word that might hang him
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