Friendship, in this case, is frank and unflinching. It has led to a humane and likeable portrait of a person who did not seek popularity, and perhaps did more than he needed to avoid it. As Prideaux demonstrates time and again, Strindberg was exquisitely non-strategic in his relationships, and found no end of ways of offending people. His blunt and merciless appraisal of the women in his life, his friends, and even the most supportive of colleagues made his collection of detractors, which included the Swedish Academy, almost redundant.

Between rows, his friends included Georg Brandes, Edvard Munch, and Paul Gauguin, and members of a Swedish artistic community that, from early on in his career, did not quite know how to deal with Strindberg but knew they would have to do so. Although Strindberg was never rich, he was during his lifetime recognised as the country’s most important writer. Shortly before his death in 1912, he was awarded the anti-Nobel Prize by a nation upset by the Academy’s oversight, which, as on other occasions, was great. Even in the thick of his troubles, spurred on by constant money problems and perhaps also by the conviction that you should write ‘in the grip of powerful emotion’, of which he had plenty, Strindberg maintained an intensity of production that led to an oeuvre of more than sixty plays, three books of poetry, eighteen novels, and nine autobiographies. In his spare time he pursued serious and eccentric scientific experiments, the occult, photography, and painted works of art that are taken as seriously as his writing.

Strindberg’s best-known play, Miss Julie, retains a prominent place, but a blind spot covers much of his other writing, as, with the exception of Ibsen, it does experimental Scandinavian literature more generally. Strindberg’s vast range of activity could make his a difficult life to catch in a four-hundred page biography, at least without imposing a false unity that would owe too much to hindsight or the biographer’s own critical concerns, and most probably sap the energy out of a life that is appealing and interesting, at least in part, because of its haphazard nature.

Prideaux’s answer – her way of making Strindberg more approachable – is to match his madness, bluntness, and ‘infinite capacity to alienate people with influence’ with a clinically sharp but rather fond account that accepts his jumbled life as the basis of a certain kind of narrative unity. Prideaux joins rather than oversees Strindberg’s life. The equality between biographer and subject makes the book a pleasure to read, but, just as importantly, it makes a complex person like Strindberg much easier for us to meet. The high, experimental nature of his work finds an approachable focal point in Prideaux’s grounded prose, a lightning rod that insists on the primary interpretative value of his everyday life.

Making connections between an author’s life and the meaning of their work can quickly become a reductive exercise. But in this case it works, for dissecting Strindberg was what Strindberg did, too. ‘Even more so than most, he is a writer whose life illuminates his work.’ In merging life and literature, the biography adopts Strindberg’s belief that examining the particulars of life is the best way of asking questions about what lies behind it. He liked the idea that we learn about the invisible through a close examination of the visible, an inductive method that helps explain his abiding love of science, and one that allows writers, including biographers, to stay on the task of detailed observation and analysis.

On the quite rare occasions that Prideaux does adopt a broader critical perspective, the question that she returns to most consistently – the invisible element that she locates in the particulars of Strindberg’s life – concerns the link between creativity and crisis. Not all writers need to be tormented in order to write well, but in Strindberg’s case a large and varied output was matched by an equally impressive array of crises: a sense of exile from Sweden that followed on from an unsuccessful prosecution against him for blasphemy; relentless financial troubles that made it difficult for him to provide for his children; a preoccupation with occult science that eventually led to a spiritual breakdown; and, perhaps most acutely, three failed marriages that became the source material for his domestic plays and kept Strindberg uncomfortably close to replicating the conditions of his own childhood.

The biography opens with Miss Julie, a play that Prideaux locates among a bizarre collection of events that influenced its composition in Denmark in 1888, including the revelation that Strindberg’s first wife, Countess Siri von Essen, had been unfaithful to him some five years before. It is a wonderful first chapter, a vignette that could form the template for this style of biography, one that insists on the inseparability of art and the context of its production. Prideaux’s particular skill lies in her representation of the dialogue that comes to exist between Strindberg, his plays, and the people around him whom he uses to populate his work with characters and ideas: his family, his hosts, contemporary literary circles, and a Copenhagen that was ready and hoping to be shocked.

The opening chapter is given a second task as prologue to the biography’s first act, one that will eventually return to Miss Julie. It begins by taking us from Strindberg’s childhood in Stockholm and his terrible relationship with his father to a creative and intellectual eclecticism that he developed during his student years. It was during this time that he discovered that ‘the esoteric underlies the exoteric if you will only open your ears to the subtext the author has imprisoned in the text’, a view that animated his subsequent attitude toward virtually all aspects of the everyday.

In 1875 he met Siri and encountered a love that drove him first to attempt suicide before recalling him to an unsteady existence as a family man. The couple had a tempestuous marriage, one that drives the first half of the book towards its rather desperate closing scenes, and stands over the second in failed anticipation of Strindberg’s ever finding anything quite as powerful as his love for Siri. Importantly for Prideaux, the marriage furnished Strindberg not only with drama but also with what were, at the time, radical ideas of gender equality that upset conservatives and contemporary aristocratic feminists alike. Both felt that his views went too far – as, arguably, did his artistic method. ‘It was not enough for Strindberg the anatomist to dissect his own living corpse; he must investigate the living corpses of others as far as he possibly could.’ Combined with an inability to temper these investigations and the fact that he liked to write during periods of crisis, the close examination of others inevitably left lasting wounds. Eventually, Siri had little choice but to spare herself. She stopped reading his work.

Making Strindberg more approachable does not mean apologising for his uncompromising mode of analysis. After all, it was his great strength as a writer. And neither is Prideaux setting us up to dislike Siri as a way of making Strindberg’s behaviour more palatable. She does take some care in showing that Strindberg was a devoted and involved father, and that he was at home with their children when Siri had her affair in Finland. If such details are presented without judgement, they nevertheless help us to understand Strindberg’s unsparing depictions of the breakdown of the marriage.

But, as with all writers, Strindberg’s harshness lay not only in anatomising life in order to make art, but in the fact that the artefact remained after the crisis was over, and remains all these years on. Watching a dress rehearsal of The Father, ‘he saw for the first time what he had done to Siri. He realized that she had been vilified in the piece; he also saw for the first time that the character of the father is, in a way, insane.’

Strindberg’s experiments in creative dissection, though quite possibly mad, are enduringly fascinating. After he and Siri separated, his search for universal meaning in the particular took him into two more marriages and radical social and artistic experimentation in Berlin, Paris, and eventually even his hometown of Stockholm. In each, he sought out what even sane writers like Prideaux are looking for, ‘the other side of the threshold’ – the invisible world that in this brilliant biography is made more understandable and more gripping by being harnessed so tightly to Strindberg’s chaotic sense of the real.