‘It was a queer, sultry summer, the summer they electrocuted the Rosenbergs, and I didn’t know what I was doing in New York.’ A great opening line: nervous, brittle, crackling withheat, with sweat, with real electricity and the threat of more, and the smell of something a little foul that wafts across the rest of this novel’s vivid pages, written in just 70 feverish days.

The Bell Jar is Sylvia Plath’s only novel, published in the UK under a pseudonym weeks before her death in 1963. It depicts an intense coming-of-age for Esther Greenwood – in New York, she’s one of 12 female college students interning at a fashion magazine. Plath, a student at Smith College in 1953, also spent that sultry summer interning at Mademoiselle. Like Esther, Plath did not have the time of her life. Like Esther, her mental health was fragile, precipitating a breakdown, an extended hospital stay and electroshock therapy. The similarities between Esther and Sylvia don’t end here.

It’s impossible to read The Bell Jar isolated from the stamp of autobiography. But it persists as a classic of American mid-century fiction for reasons besides, especially in how perfectly it encapsulates the historical period and how coolly it details Esther’s brutal depression. Almost everything Esther encounters disgusts her. ‘I’m neurotic as hell,’ she remarks, for wanting two mutually exclusive things at once. Rigid social expectations contribute to her crisis and Plath describes them – a life of domesticity at war with Esther’s desire to write – in blackly funny ways that temper the emotional desperation.

But Plath isn’t writing social history, she’s writing fiction. She’s not providing a clinical investigation of depression, she’s conveying the muck of what it feels like, and what it feels like most often is chaotic, isolating and strange. Esther’s mental illness is never romantic or glamorous – it’s human. Like her creator, she is very much alive, and The Bell Jar moves towards its conclusion chasing the strong, steady rhythm of her beating heart.

Joanna Di Mattia is a bookseller at Readings Carlton.