<P> Rochester explains that he was not warned that violent insanity and intellectual disability ran in the Mason family and that the past three generations succumbed to it . He assumed Bertha's mother to be dead and was never told otherwise, but she was in fact locked away in an asylum . Bertha also had an intellectually disabled younger brother . Rochester's father knew of this but did not bother to tell his son, caring only about the vast fortune the marriage would bring him, and the Mason family clearly wanted Bertha off their hands as quickly as possible . Rochester asserts that Bertha's mental health deteriorated quickly, though it is unclear which form of mental illness she suffers from . Her insane, violent behaviour becomes frightening to behold . She crawls on all fours, snarling, and behaving in a bestial manner . </P> <P> Rochester returns with her to England and has her imprisoned in a third floor room off the gallery for ten years with Grace Poole, a hired nurse who keeps her under control while Rochester travels abroad to forget his horrible marriage . However, Grace drinks sometimes, and Bertha manages to escape, causing havoc in the house: starting a fire in Mr Rochester's bed and biting and stabbing her own visiting brother . </P> <P> Rochester's marriage to Bertha eventually stands in the way of his marrying Jane Eyre, who is unaware of Bertha's existence and whom he truly loves (though he later admits to Jane that he once thought he loved Bertha). As Bertha is insane he cannot divorce her, due to her actions being uncontrollable and thus not legitimate grounds for divorce . Years of violence, insanity, and confinement in an attic destroy Bertha's looks: when she sees Bertha in the middle of the night, Jane describes Bertha as looking "savage", even going so far as to compare her with a "German vampire". Bertha destroys Jane's wedding veil (an action that hints that Bertha is at least sane enough to be aware that her husband is planning to enter a bigamous marriage). Despite not loving her, Rochester attempts to save Bertha from an enormous fire she starts in the house when she again escapes . Bertha perishes after she throws herself off the roof, leaving her husband free to marry Jane . </P> <P> In Wide Sargasso Sea, "Bertha Mason" is portrayed as being a false name for Antoinette Cosway . The book purports to tell Antoinette's side of the story as well as Rochester's and detail how she ended up alone and raving in the attic of Thornfield Hall . According to the book, Antoinette's insanity and drunkenness are the result of Rochester's misguided belief that madness is in her blood and that she was part of the scheme to have him married blindly . </P>

Character sketch of bertha mason in jane eyre