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We didn't know the nature of lightning or rainbows for three and a half million years, pet. Don't reject it just because it seems impossible. If we closed our minds, there would never be the Gravitube, antimatter, Prose Portals, thermos flasks—"
"Wait!" I interrupted. "How does a thermos fit in with that lot?"
Because, my dear girl," replied Mycroft, cleaning the blackboard and drawing a crude picture of a thermos with a question mark, "no one has the least idea why they work." He stared at me for a moment and continued: "You will agree that a vacuum flask keeps hot things hot in the winter and cold things cold in the summer?"
"Yes—?"
"Well, how does it know? I've studied vacuum flasks for many years and not one of them gave any clues as to their inherent seasonal cognitive ability. It's a mystery to me, I can tell you.
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