There’s something about the feeling of finally standing in front of a painting that you have only known through the pages of books. It is not just the psychological shifting of dimensions (they are usually bigger, or smaller, than you imagined), but a sort of stirring recognition: “There you are.”

The surge of emotion I felt standing in front of Susannah and the Elders – painted by a 17-year-old Artemisia Gentileschi in the same year she was raped by the artist who was hired by her father Orazio to teach her – was as powerful as any I have felt in my life. In it, a nude Susannah twists away from the two old letches with horror and disgust; unlike many of the nudes painted by male artists, her body is not an exercise in containment, static and mannered as though it could have been carved from marble: it is living, moving flesh.

Why this painting? Why now, as the first exhibition dedicated to the work of Artemisia opens at the National Gallery? I haven’t visited a museum or art gallery in months, so there is that. But also: I have spent years thinking about this painting and this artist. She means something to me, as she does to the many feminist art historians who have dedicated their research to her, and the many, many other women who have admired and empathised with her art. And empathy is of course key: many women will look at Susannah and think, “been there”.

Artemisia was a survivor of male violence, just as I am. Tears sprang to my eyes when I looked at the transcript of her torture during her rapist’s trial, and read that she had repeated “è vero, è vero, è vero” (“it is true, it is true, it is true”). In her later version of Judith Beheading Holofernes, the man’s hair pokes through between her tightened knuckles as she holds him down while cutting off his head. This has been called a revenge fantasy, and it is one Gentileschi returns to. At the National Gallery, we also see the aftermath: the head in a basket, Judith and her maidservant turning as though they have heard a noise, complicit in their crime.

The rape is important because without this vital piece of context our understanding of this great artist will always be limited. A large part of why Gentileschi captivates is because she triumphed against patriarchy. Despite the many barriers that existed for women artists in her time – the 17th century – she was hugely famous. There is also her reclamation by feminist art historians after years of dismissal by the male art establishment (she can only be called an undiscovered genius if you are deliberately ignoring many decades of feminist writing and scholarship).