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Furthermore: concerning these last mentioned Leviathans, they have two firm fortresses, which, in all human probability, will for ever remain impregnable. And as upon the invasion of their valleys, the frosty Swiss have retreated to their mountains; so, hunted from the savannas and glades of the middle seas, the whale-bone whales can at last resort to their Polar citadels, and diving under the ultimate glassy barriers and walls there, come up among icy fields and floes; and in a charmed circle of everlasting December, bid defiance to all pursuit from man.