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which literary technique is used in this excerpt from frankenstein by mary shelley?

my life, as it passed thus, was indeed hateful to me, and it was during sleep alone that i could taste joy. o blessed sleep! often, when most miserable, i sank to repose, and my dreams lulled me even to rapture. the spirits that guarded me had provided these moments, or rather hours, of happiness that i might retain strength to fulfil my pilgrimage. deprived of this respite, i should have sunk under my hardships. during the day i was sustained and inspirited by the hope of night, for in sleep i saw my friends, my wife, and my beloved country; again i saw the benevolent countenance of my father, heard the silver tones of my elizabeth's voice, and beheld clerval enjoying health and youth. often, when wearied by a toilsome march, i persuaded myself that i was dreaming until night should come and that i should then enjoy reality in the arms of my dearest friends. what agonizing fondness did i feel for them! how did i cling to their dear forms, as sometimes they haunted even my waking hours, and persuade myself that they still lived! at such moments vengeance, that burned within me, died in my heart, and i pursued my path towards the destruction of the daemon more as a task enjoined by heaven, as the mechanical impulse of some power of which i was unconscious, than as the ardent desire of my soul. what his feelings were whom i pursued i cannot know. sometimes, indeed, he left marks in writing on the barks of the trees or cut in stone that guided me and instigated my fury. "my reign is not yet over"—these words were legible in one of these inscriptions—"you live, and my power is complete. follow me; i seek the everlasting ices of the north, where you will feel the misery of cold and frost, to which i am impassive. you will find near this place, if you follow not too tardily, a dead hare; eat and be refreshed. come on, my enemy; we have yet to wrestle for our lives, but many hard and miserable hours must you endure until that period shall arrive."

scoffing devil! again do i vow vengeance; again do i devote thee, miserable fiend, to torture and death. never will i give up my search until he or i perish; and then with what ecstasy shall i join my elizabeth and my departed friends, who even now prepare for me the reward of my tedious toil and horrible pilgrimage!

1. analogy
2. flashback
3. foil paradox stream of consciousness
4. flash-forward