There aren’t many writers who radically remake their style over the course of their life: we might think of Joyce’s revolutions, Woolf’s renewals, or what Jeanette Winterson called the “furnace work” that Eliot undertook on his mature style for Four Quartets.

Rarer still are those who change the language they write in, but to names such as Beckett and Nabokov we can add Jhumpa Lahiri. At the turn of the millennium, Lahiri was a young star of American literature, winning a Pulitzer prize for her debut, Interpreter of Maladies. She could have carried on like that, but little over a decade later, after publication of her novel The Lowland in 2013, she stopped writing in English and took up Italian.

The results so far have been rewarding: the account of her language shift, In Other Words (2016); her extraordinary novel Whereabouts (2021); and her selections, translations and annotations for The Penguin Book of Italian Short Stories (2019), the best anthology of its kind I’ve read.

Now we have Translating Myself and Others, a collection of essays on translation. As Lahiri notes, “I was a translator before I was a writer”: her mother tongue is Bengali, and in In Other Words she wrote of the “continuous sense of estrangement” this gave her in America. Her move to Italian was perhaps a form of taking control, of choosing her own estrangement.

She writes of the appeal and challenges of writing in Italian. She feels like an impostor, a sense not alleviated when Italians ask her why she is writing “in our language”, or when a newspaper refers to her work as “my ‘Italian’ poems”. (“Why ‘Italian’ in scare quotes? Is it because I write in an Italian that’s false, spurious, slanted, nonexistent?”) She vents frustration on translation being seen as “imitative as opposed to imaginative”, and is persuasive on the difficulty of translating your own work: “There are no rules to obey when the only authority is oneself.” These self-appraisals are more interesting than the rather technical essays on other writers (three of which are on her friend Domenico Starnone’s novels).

Lahiri writes in Italian to “feel free” but also values how it makes her slow down – “I knocked on this door quite late, and it creaks a little” – and think differently, like a modernist painter who restricts herself to two colours to learn how it makes her see. A new language, she writes, is a form of blindness, but “I believe I’m blind even in English, only in reverse. Familiarity, dexterity and ease with a language can confer another form of blindness.”

That is not the only blind spot in a book that shows too little of the “myself” in the title. The hole that runs throughout is the answer to why Lahiri moved to Italy, and to Italian, in the first place. She didn’t answer it in In Other Words and she doesn’t here. Is it simply that, as Leopardi put it, “no language has enough words and phrases to correspond to and express all the infinite subtleties of thought”?

No. To return to Winterson on Eliot: “It is clear that [his] stylistic development, from The Waste Land to Four Quartets, is an emotional development of a profound order.” It is equally clear that Lahiri’s is too. But we get only hints of this momentous change: she had “run away” to Italy, “taking refuge in the Italian language in search of freedom and happiness”. One piece is written “during a particularly challenging year of my life”. Why provoke curiosity you won’t satisfy? Without seeing the input that led to the output, we feel as she does in her essay on Gramsci’s prison letters: “We experience only a single strand of a double thread.”

There is, however, a switch right at the end, in an afterword where Lahiri returns to the book best suited to any writer in the business of transformation: the Metamorphoses. “Ovid’s great poem, for me, is the sun.” She recounts the story of her mother’s decline in health, and death, in 2021, when Lahiri derives consolation from Ovid’s lines. “My soul stirs to speak of forms changed into new bodies.” Suddenly, when it is almost too late, this cool, detached book bristles with life and love.

• Translating Myself and Others by Jhumpa Lahiri is published by Princeton University Press (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply