Literary Device - Symbol (Bertha Mason)

"She bit me. She worried me like a tigress, when Rochester got the knife from her...She sucked the blood: she said she'd drain my heart".

This speech takes place after Richard Mason has been attacked by Bertha. Although Mr. Rochester forbids Jane and Richard Mason to speak about what has occurred, Jane cannot help overhearing this clue to the mystery of Thornfield. Through Mason's description, Bronte is able to present Bertha's nature as bestial and even vampiric, a term in itself that alludes to the Gothic literary tradition. Not only is Bertha akin to the animal world in all its chaos, she is even carnivorous and attempts to suck the life out of her brother in the same way that her presence threatens to suck the life out of Mr. Rochester's happiness with Jane. Bertha's uncontrollable animal nature comes in stark contrast to Jane's placidity and rationality; although Jane possesses some of the same fiery passion that Bertha has, Jane is able to control her inclinations with her humanity.

I believe Bertha Mason is Jane's alter-ego. Her "madness" Bertha is living out Jane's inner world of passion (be it her anger, her sexuality, her intellect) that Jane dare not exhibit in her outer world. We see, in this scene, sharp parallels with Jane's experience in the Red Room (Chapter 2) notably her being forcibly restrained by the two servants, just as Bertha is restrained in this chapter by Rochester. Bertha is living the life Jane is sacred of living. Deep down (because of her past) I think Jane is scared Rochester will find love elsewhere and dump her our lock her up like he did to Bertha. Rochester claims that she was drunken and promiscuous and that her excesses brought on her madness when she was young, but he’s not exactly an objective witness, and that's why she was locked in the attic.