“You either see it or you don’t. It’s all there. There’s nothing up its sleeve. The trick lies in the fact that, like all great mystifications, it wears the cloak of invisibility. I do not use the word ‘great’ loosely. It’s just that ― a great conception ― and it wouldn’t surprise me if it takes its place among the classic inventions of the criminal mind.”
“For God’s sake,” burst out Crowe Macgowan, “talk something that makes sense!”
“Mac,” said Ellery, “what are frogs and toads?”
“What are frogs and toads?”
“That’s right. What kind of animals are they?”
Macgowan looked blank.
“Amphibians,” said old Mr. Collier.
“Thank you, Mr. Collier. And what are alligators?”
“Alligators are reptiles.”
“The wallet derived from a reptile. And to which family of animals do cats and dogs belong?”