The Spectral Horseman by Percy Bysshe Shelley

What was the shriek that struck Fancy's ear / As it sate on the ruins of time that is past? / Hark! it floats on the fitful blast of the wind, / And breathes to the pale moon a funeral sigh. / It is the Benshie's moan on the storm, / Or a shivering fiend that thirsting for sin, / Seeks murder and guilt when virtue sleeps, / Winged with the power of some ruthless king, / And sweeps o'er the breast of the prostrate plain. / It was not a fiend from the regions of Hell / That poured its low moan on the stillness of night: / It was not a ghost of the guilty dead, / Nor a yelling vampire reeking with gore; / But aye at the close of seven years' end, / That voice is mixed with the swell of the storm, / And aye at the close of seven years' end, / A shapeless shadow that sleeps on the hill / Awakens and floats on the mist of the heath. / It is not the shade of a murdered man, / Who has rushed uncalled to the throne of his God, / And howls in the pause of the eddying storm. / This voice is low, cold, hollow, and chill, / 'Tis not heard by the ear, but is felt in the soul. / 'Tis more frightful far than the death-daemon's scream, / Or the laughter of fiends when they howl o'er the corpse / Of a man who has sold his soul to Hell. / It tells the approach of a mystic form, / A white courser bears the shadowy sprite; / More thin they are than the mists of the mountain, / When the clear moonlight sleeps on the waveless lake. / More pale HIS cheek than the snows of Nithona, / When winter rides on the northern blast, / And howls in the midst of the leafless wood. / Yet when the fierce swell of the tempest is raving, / And the whirlwinds howl in the caves of Inisfallen, / Still secure mid the wildest war of the sky, / The phantom courser scours the waste, / And his rider howls in the thunder's roar. / O'er him the fierce bolts of avenging Heaven / Pause, as in fear, to strike his head. / The meteors of midnight recoil from his figure, / Yet the ‘wildered peasant, that oft passes by, / With wonder beholds the blue flash through his form: / And his voice, though faint as the sighs of the dead, / The startled passenger shudders to hear, / More distinct than the thunder's wildest roar. / Then does the dragon, who, chained in the caverns / To eternity, curses the champion of Erin, / Moan and yell loud at the lone hour of midnight, / And twine his vast wreaths round the forms of the daemons; / Then in agony roll his death-swimming eyeballs, / Though ‘wildered by death, yet never to die! / Then he shakes from his skeleton folds the nightmares, / Who, shrieking in agony, seek the couch / Of some fevered wretch who courts sleep in vain; / Then the tombless ghosts of the guilty dead / In horror pause on the fitful gale. / They float on the swell of the eddying tempest, / And scared seek the caves of gigantic... / Where their thin forms pour unearthly sounds / On the blast that sweets the breast of the lake, / And mingles its swell with the moonlight air.