A bell jar is a metaphor for loneliness in a mental illness. The protagonist lives in a vicious circle of her thoughts and anxieties. To achieve improvement, she needs to lift the bell jar. However, Esther needs medical help to do that. At the end of the book, the bell jar gets slightly raised, but the girl still feels it over her head like the sword of Damocles, waiting to fall at any moment.
What does The Bell Jar mean? The meaning of the title can open the symbolism of the book.
A bell jar is a glass jar put upside down. It is used to display a scientific phenomenon, like a specific kind of gas or vacuum. Some plants are covered with bell jars to create an unchangeable atmosphere for vulnerable species. Literature authors used this object as a metaphor for protection from the adverse outside world. For example, the Little Prince in the tale by Antoine de Saint-Exupéry covered his rose with a glass globe to protect it.
For Esther, a bell jar is both a way of self-protection and isolation. From first sight, it is her imaginary coping mechanism with the adverse reality. Meanwhile, the cover creates a limited area where no outside air penetrates. The protagonist suffocates inside her inner world, descending from depression to madness.
The bell jar distorts Esther’s vision of the world. She can no longer recognize her reflection in the mirror. She does not wash because she thinks it has no point. After all, if she is closed within her own atmosphere, nobody can see or smell her. But the cover is transparent, and the onlookers can watch her wither. Esther cannot build a sincere connection with a friend or lover because the glass walls of her mind separate them.