"Its title, the bell jar, is a metaphorical explanation for what [Esther's] insanity felt like. It is suffocating; it closes her off from the world. When it descends, she cannot see or hear clearly and she is trapped alone."
Through the course of the novel Esther Greenwood goes through three stages, Pre-Treatment, Treatment, and Post-Treatment for her insanity. Before her treatment Esther works in New York, becomes bitterly depressed, and finally attempts suicide. During her treatment, Esther can feel the bell jar descending as she struggles with her insanity. After her treatment, Esther is sexually frustrated and emotionally drained.
Prior to her treatment Esther is working in New York, on scholarship, as an intern editor, for "Ladies Day Magazine." Her boss, Jay Cee, is very harsh and demanding of her. At this point in the novel there is no 'bell-jar'. After her period as an intern and some failed relationships, Esther goes back home and finds that she was not accepted into a creative writing class that she had been hoping for. This rejection along with her troubles in New York cause her to fall into a self-destructive depression in which Esther is unable to write or do normal activities. She is taken to a psychiatrist that prescribes shock therapy. The shock therapy that she receives does not go over well, Esther's body is contorted and her bones felt as if they were being torn from her body. The failed shock therapy does not improve Esther's state, rather, it makes it worse, further depressing Esther and causing her to try and commit suicide, twice. Toward the end of this portion of the novel, the bell jar begins descending along with Esther's insanity.
After Esther's failed suicide she is taken to a private hospital where she is to be treated. It is actually during this time...