"Professor," he told me, "the simple logic of the naturalist led me to discover this passageway, and I alone am familiar with it. I'd noted that in the Red Sea and the Mediterranean there exist a number of absolutely identical species of fish: eels, butterfish, greenfish, bass, jewelfish, flying fish. Certain of this fact, I wondered if there weren't a connection between the two seas. If there were, its underground current had to go from the Red Sea to the Mediterranean simply because of their difference in level. So I caught a large number of fish in the vicinity of Suez. I slipped copper rings around their tails and tossed them back into the sea. A few months later off the coast of Syria, I recaptured a few specimens of my fish, adorned with their telltale rings. So this proved to me that some connection existed between the two seas. I searched for it with my Nautilus, I discovered it, I ventured into it; and soon, professor, you also will have cleared my Arabic tunnel!"