They kept recommending novels to each other, and to friends and family, for many years, and, in 2007, when the philosopher Alain de Botton, a fellow Cambridge classmate, was thinking about starting the School of Life, they pitched to him the idea of running a bibliotherapy clinic. “As far as we knew, nobody was doing it in that form at the time,” Berthoud said. “Bibliotherapy, if it existed at all, tended to be based within a more medical context, with an emphasis on self-help books. But we were dedicated to fiction as the ultimate cure because it gives readers a transformational experience.”

Berthoud and Elderkin trace the method of bibliotherapy all the way back to the Ancient Greeks, “who inscribed above the entrance to a library in Thebes that this was a ‘healing place for the soul.’ ” The practice came into its own at the end of the nineteenth century, when Sigmund Freud began using literature during psychoanalysis sessions. After the First World War, traumatized soldiers returning home from the front were often prescribed a course of reading. “Librarians in the States were given training on how to give books to WWI vets, and there’s a nice story about Jane Austen’s novels being used for bibliotherapeutic purposes at the same time in the U.K.,” Elderkin says. Later in the century, bibliotherapy was used in varying ways in hospitals and libraries, and has more recently been taken up by psychologists, social and aged-care workers, and doctors as a viable mode of therapy.

There is now a network of bibliotherapists selected and trained by Berthoud and Elderkin, and affiliated with the School of Life, working around the world, from New York to Melbourne. The most common ailments people tend to bring to them are the life-juncture transitions, Berthoud says: being stuck in a rut in your career, feeling depressed in your relationship, or suffering bereavement. The bibliotherapists see a lot of retirees, too, who know that they have twenty years of reading ahead of them but perhaps have only previously read crime thrillers, and want to find something new to sustain them. Many seek help adjusting to becoming a parent. “I had a client in New York, a man who was having his first child, and was worried about being responsible for another tiny being,” Berthoud says. “I recommended ‘Room Temperature,’ by Nicholson Baker, which is about a man feeding his baby a bottle and having these meditative thoughts about being a father. And of course 'To Kill a Mockingbird,' because Atticus Finch is the ideal father in literature.”

Berthoud and Elderkin are also the authors of “The Novel Cure: An A-Z of Literary Remedies,” which is written in the style of a medical dictionary and matches ailments (“failure, feeling like a”) with suggested reading cures (“The History of Mr. Polly,” by H. G. Wells). First released in the U.K. in 2013, it is now being published in eighteen countries, and, in an interesting twist, the contract allows for a local editor and reading specialist to adapt up to twenty-five per cent of the ailments and reading recommendations to fit each particular country’s readership and include more native writers. The new, adapted ailments are culturally revealing. In the Dutch edition, one of the adapted ailments is “having too high an opinion of your own child”; in the Indian edition, “public urination” and “cricket, obsession with” are included; the Italians introduced “impotence,” “fear of motorways,” and “desire to embalm”; and the Germans added “hating the world” and “hating parties.” Berthoud and Elderkin are now working on a children’s-literature version, “A Spoonful of Stories,” due out in 2016.

For all avid readers who have been self-medicating with great books their entire lives, it comes as no surprise that reading books can be good for your mental health and your relationships with others, but exactly why and how is now becoming clearer, thanks to new research on reading’s effects on the brain. Since the discovery, in the mid-nineties, of “mirror neurons”—neurons that fire in our brains both when we perform an action ourselves and when we see an action performed by someone else—the neuroscience of empathy has become clearer. A 2011 study published in the Annual Review of Psychology, based on analysis of fMRI brain scans of participants, showed that, when people read about an experience, they display stimulation within the same neurological regions as when they go through that experience themselves. We draw on the same brain networks when we’re reading stories and when we’re trying to guess at another person’s feelings.

Other studies published in 2006 and 2009 showed something similar—that people who read a lot of fiction tend to be better at empathizing with others (even after the researchers had accounted for the potential bias that people with greater empathetic tendencies may prefer to read novels). And, in 2013, an influential study published in Science found that reading literary fiction (rather than popular fiction or literary nonfiction) improved participants’ results on tests that measured social perception and empathy, which are crucial to “theory of mind”: the ability to guess with accuracy what another human being might be thinking or feeling, a skill humans only start to develop around the age of four.

Keith Oatley, a novelist and emeritus professor of cognitive psychology at the University of Toronto, has for many years run a research group interested in the psychology of fiction. “We have started to show how identification with fictional characters occurs, how literary art can improve social abilities, how it can move us emotionally, and can prompt changes of selfhood,” he wrote in his 2011 book, “Such Stuff as Dreams: The Psychology of Fiction.” “Fiction is a kind of simulation, one that runs not on computers but on minds: a simulation of selves in their interactions with others in the social world…based in experience, and involving being able to think of possible futures.” This idea echoes a long-held belief among both writers and readers that books are the best kinds of friends; they give us a chance to rehearse for interactions with others in the world, without doing any lasting damage. In his 1905 essay “On Reading,” Marcel Proust puts it nicely: “With books there is no forced sociability. If we pass the evening with those friends—books—it’s because we really want to. When we leave them, we do so with regret and, when we have left them, there are none of those thoughts that spoil friendship: ‘What did they think of us?’—‘Did we make a mistake and say something tactless?’—‘Did they like us?’—nor is there the anxiety of being forgotten because of displacement by someone else.”

George Eliot, who is rumored to have overcome her grief at losing her life partner through a program of guided reading with a young man who went on to become her husband, believed that “art is the nearest thing to life; it is a mode of amplifying experience and extending our contact with our fellow-men beyond the bounds of our personal lot.” But not everybody agrees with this characterization of fiction reading as having the ability to make us behave better in real life. In her 2007 book, “Empathy and the Novel,” Suzanne Keen takes issue with this “empathy-altruism hypothesis,” and is skeptical about whether empathetic connections made while reading fiction really translate into altruistic, prosocial behavior in the world. She also points out how hard it is to really prove such a hypothesis. “Books can’t make change by themselves—and not everyone feels certain that they ought to,” Keen writes. “As any bookworm knows, readers can also seem antisocial and indolent. Novel reading is not a team sport.” Instead, she urges, we should enjoy what fiction does give us, which is a release from the moral obligation to feel something for invented characters—as you would for a real, live human being in pain or suffering—which paradoxically means readers sometimes “respond with greater empathy to an unreal situation and characters because of the protective fictionality.” And she wholeheartedly supports the personal health benefits of an immersive experience like reading, which “allows a refreshing escape from ordinary, everyday pressures.”