Jane Eyre and Bertha Mason are foils for one another, representing opposite responses to Mr. Rochester's bad behavior toward them. For example, when Jane finds out in Chapter 26 that Mr. Rochester is already married, she remains composed:
My nerves vibrated to those low-spoken words as they had never vibrated to thunder – my blood felt their subtle violence as it had never felt frost or fire; but I was collected, and in no danger of swooning.
Jane has every reason to be upset not only internally, but also outwardly. She and Mr. Rochester are in the middle of their own wedding ceremony when a lawyer stands up to drop this bombshell. As if the shock were not enough, Mr. Rochester has previously worked hard to convince Jane that she is the only bride for him. Jane's nerves "vibrate" and her blood feels at once hotter and colder than she has ever felt it. Her ability to keep herself "collected" is practically superhuman in this moment where her very body feels like it's breaking all the laws of the natural world. Her composure reflects the rationality she has carefully disciplined into herself since leaving Gateshead as a child.
Bertha, meanwhile, represents the wronged woman who surrenders completely to emotion. Later in Chapter 26, Mr. Rochester takes a procession of people up to the attic to witness Bertha's madness (which, according to him, explains why she hardly counts as a wife):
Mr Rochester flung me behind him: the lunatic sprang and grappled his throat viciously, and laid her teeth to his cheek: they struggled. She was a big woman, in stature almost equalling her husband, and corpulent besides: she showed virile force in the contest – more than once she almost throttled him, athletic as he was.
Jane notices that while everyone seems to think of Bertha simply as an animal, a "lunatic" who is not in control of her actions, she in fact directs her anger and violence toward Mr. Rochester, the man who has imprisoned her in the attic. Recall that earlier in the novel, she set fire not to the attic but to Mr. Rochester's bed. Her outbursts are personal. Unlike Jane, Bertha has allowed her anger at Mr. Rochester to drive her to violence.
As Jane's foil, Bertha is both a cautionary tale and a representation of Jane's emotional inner world. Rochester has wronged both of these women. Internally, they share intense feelings about what he has done to them. Jane has learned to suppress the kind of outburst Bertha is having (one that is not all that dissimilar to outbursts Jane had toward John Reed), and the novel suggests that this skill of suppression has saved Jane from becoming a "madwoman" who must be locked away like Bertha. But as Jane will come to discover when she tries to live with St. John Rivers, entirely suppressed emotion leads to a stifled life as well. Jane's "development" over the course of the novel involves learning to be a little like Bertha without letting emotion overtake her rational self.
Mr. Rochester and St. John Rivers are foils for one another, representing stormy emotions on the one hand and detached rationality on the other. An example of St. John's detached rationality occurs in Chapter 30, when the narrator tries to describe one of St. John's sermons:
When he had done, instead of feeling better, calmer, more enlightened by his discourse, I experienced an inexpressible sadness: for it seemed to me – I know not whether equally so to others – that the eloquence to which I had been listening had sprung from a depth where lay turbid dregs of disappointment, where moved troubling impulses of insatiate yearnings and disquieting aspirations.
St. John is by all accounts a good Christian. He goes out every day to help his neighbors, and he preaches sermons that perfectly reflect Calvinist doctrine. Still, Jane can't shake the sense that St. John treats doctrine as an instruction manual for behavior rather than a guide to spirituality. While St. John is a perfect Christian on paper, Jane thinks his rigidity may be keeping him from a real connection with God. He is not giving into enough of his "impulses of insatiate yearnings" and is thus living a life of disappointment.
By contrast, Mr. Rochester is always following his impulses. In Chapter 32, the narrator describes dreaming about Mr. Rochester during her stay with the Rivers family:
I used to rush into strange dreams at night: dreams many-coloured, agitated, full of the ideal, the stirring, the stormy – dreams where, amidst unusual scenes, charged with adventure, with agitating risk and romantic chance, I still again and again met Mr Rochester, always at some exciting crisis [...]
In Jane's mind, Mr. Rochester is "stormy," representing "risk and romantic chance." Mr. Rochester is much more mercurial than St. John and represents less safety and stability—Jane was often very upset on his account when she was at Thornfield. But she was never bored, which she can't say of the time she spends around St. John. Jane needs to read historical romances and dream of Mr. Rochester to pass the time with St. John. With Mr. Rochester, Jane's life provided her with all the adventure she could want.
The two men bring out different sides of Jane's personality, too. Mr. Rochester brings out her impulsive, emotional side, and St. John brings out her rational, calm side. Although Jane ends up with Mr. Rochester, it is important to note that their relationship does not work out until Mr. Rochester has undergone a transformation to become less dangerous. In a way modern readers might critique, the novel represents his disability at the end of the novel as the thing that tames him. Disabled after the fire that destroys both Bertha and Thornfield, Mr. Rochester is all out of deep, dark secrets and can no longer be quite so impulsive. Jane is finally able to rationalize her relationship with him because the emotional excitement will no longer be out of hand.
Mr. Rochester and St. John Rivers are foils for one another, representing stormy emotions on the one hand and detached rationality on the other. An example of St. John's detached rationality occurs in Chapter 30, when the narrator tries to describe one of St. John's sermons:
When he had done, instead of feeling better, calmer, more enlightened by his discourse, I experienced an inexpressible sadness: for it seemed to me – I know not whether equally so to others – that the eloquence to which I had been listening had sprung from a depth where lay turbid dregs of disappointment, where moved troubling impulses of insatiate yearnings and disquieting aspirations.
St. John is by all accounts a good Christian. He goes out every day to help his neighbors, and he preaches sermons that perfectly reflect Calvinist doctrine. Still, Jane can't shake the sense that St. John treats doctrine as an instruction manual for behavior rather than a guide to spirituality. While St. John is a perfect Christian on paper, Jane thinks his rigidity may be keeping him from a real connection with God. He is not giving into enough of his "impulses of insatiate yearnings" and is thus living a life of disappointment.
By contrast, Mr. Rochester is always following his impulses. In Chapter 32, the narrator describes dreaming about Mr. Rochester during her stay with the Rivers family:
I used to rush into strange dreams at night: dreams many-coloured, agitated, full of the ideal, the stirring, the stormy – dreams where, amidst unusual scenes, charged with adventure, with agitating risk and romantic chance, I still again and again met Mr Rochester, always at some exciting crisis [...]
In Jane's mind, Mr. Rochester is "stormy," representing "risk and romantic chance." Mr. Rochester is much more mercurial than St. John and represents less safety and stability—Jane was often very upset on his account when she was at Thornfield. But she was never bored, which she can't say of the time she spends around St. John. Jane needs to read historical romances and dream of Mr. Rochester to pass the time with St. John. With Mr. Rochester, Jane's life provided her with all the adventure she could want.
The two men bring out different sides of Jane's personality, too. Mr. Rochester brings out her impulsive, emotional side, and St. John brings out her rational, calm side. Although Jane ends up with Mr. Rochester, it is important to note that their relationship does not work out until Mr. Rochester has undergone a transformation to become less dangerous. In a way modern readers might critique, the novel represents his disability at the end of the novel as the thing that tames him. Disabled after the fire that destroys both Bertha and Thornfield, Mr. Rochester is all out of deep, dark secrets and can no longer be quite so impulsive. Jane is finally able to rationalize her relationship with him because the emotional excitement will no longer be out of hand.