Did Mary Shelley say “Beware; for I am fearless, and therefore powerful”?

Did Mary Shelley say “Beware; for I am fearless, and therefore powerful”?

Found word for word. Yes. The text appears in works attributed to Mary Shelley. Source and location below.

The monster saw my determination in my face and gnashed his teeth in the impotence of anger. "Shall each man," cried he, "find a wife for his bosom, and each beast have his mate, and I be alone? I had feelings of affection, and they were requited by detestation and scorn. Man! You may hate, but beware! Your hours will pass in dread and misery, and soon the bolt will fall which must ravish from you your happiness forever. Are you to be happy while I grovel in the intensity of my wretchedness? You can blast my other …
Frankenstein; Or, The Modern Prometheus — Mary Wollstonecraft (Godwin) Shelley, Chapter 20 · ¶508 · Public domain (US), Project Gutenberg #84 · source

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