A gulf profound as that Serbonian bog Betwixt Damiata and Mount Casius old, Where armies whole have sunk: the parching air Burns frore, and cold performs th' effect of fire. Thither by harpy-footed Furies hal'd, At certain revolutions all the damn'd Are brought, and feel by turns the bitter change Of fierce extremes,-extremes by change more fierce; From beds of raging fire to starve in ice Their soft ethereal warmth, and there to pine Immovable, infix'd, and frozen round, Periods of time; thence hurried back to fire.