The words induced me to turn towards myself. I learned that the possessions most esteemed by your fellow-creatures were, high and unsullied descent united with riches. A man might be respected with only one of these advantages; but, without either, he was considered, except in very rare instances, as a vagabond and a slave, doomed to waste his powers for the profits of the chosen few!
-Frankenstein (1831)
I would say the main thing that defines modern incels is hatred of women and "sex havers" and while I'm not done with the book yet, I haven't seen the monster express either of those things.
I'd define them more by how self-absorbed they are and how they're unable to relate to other people solely on the metric of having a sexual partner. They can't see past themselves, and that also entails their hatred of women.
To me the best part explaining how I mean is when the monster is talking to the blind peasant guy De Lacey in Chapter 15
spoilers for a book from 1818
The monster outright refuses any sort of companionship or friendship unless it's specifically a wife that's also built by Frankenstein. I mean to be fair though, after old De Lacey tells him people are kind, his children enter the cottage and beat the shit out of the monster because he looks weird.
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