John Updike had the mind of a middling middle-class postwar American male, and the prose style of a literary genius. Such a lord of language was he that even the notoriously grudging Vladimir Nabokov afforded him a meed of praise. A reviewer, musing on the disproportion between the style and content of Updike’s fiction, likened him to a lobster with one hugely overgrown claw. It was a comparison Updike was to remember – for all his bland urbanity, on display from start to finish in this mighty volume of his letters, he could be prickly, and did not take slights lightly.

As a novelist he aimed, as he once put it, to “give the mundane its beautiful due”. Apart from a few rare and in some cases ill-advised ventures into the exotic – the court at Elsinore, Africa, the future – his abiding subject was the quotidian life of “ordinary” Americans in the decades between the end of the second world war and the coming of a new technological age in the closing years of the 20th century.

He was born in 1932 in Pennsylvania, living for 13 years in Shillington before he moved with his parents and grandparents into a farmhouse in a rural redoubt called, aptly, Plowville. He was an only child, and he loved and cared for his father and, in particular, his mother, until the end of their days.

Updike senior was a high school maths teacher who, in the Depression years, supplemented the family income by working as a road labourer. The writer’s mother, Linda, was herself a writer, who after years of rejections finally succeeded in publishing a number of stories in the New Yorker, her son’s literary home from home.

In 1950 Updike escaped the rustic life when he entered Harvard on a scholarship to study English. At college, he wrote home diligently, addressing long screeds of descriptive prose specifically to his mother – two thousand letters, notes and postcards – and to the “Plowvillians” in general. From the start he was incapable of writing a bad sentence, although the jaunty tone and frequent longueurs of the early letters do test the reader’s patience. All the same, his energy, assiduity and sharpness of eye are remarkable in one so young.

Remarkable too are his ambition and application, not to mention brass neck. He was hardly past childhood when he started putting his name about. “At age 13,” James Schiff notes, “Updike began submitting poems, drawings, and other unsolicited pieces to various magazines, including the New Yorker.” Two years later he was recommending a short story by James Thurber to Ellery Queen’s Mystery Magazine. He also courted cartoonists – he was drawn to graphic art from his earliest days – publishers, newspaper and magazine columnists, the editors of Life magazine, and even the Pentagon. Here was a boy in a hurry.

The tone throughout these many hundreds of letters is consistently equable, except on those few occasions when the writer is driven to objection or to self-defence by intrusive, abusive or presumptuous correspondents. There are abiding enmities – the critics Frederick Crews and Alfred Kazin come in for sound kickings, while Gore Vidal is a thorn Updike never managed to extract from his side – but his fondnesses far outnumber his dislikes.

Some readers, no doubt, will long for more frequent and more energetic displays of spleen. In his introduction, Schiff allows, perhaps a shade ill-advisedly, that “There is little tragedy, trauma, or pain in these letters – Updike had a good, accomplished, and satisfying life,” though he hastens to add that “there is drama, along with conflict and problems”.

The issue of censorship, however, was extremely problematic in his start-up years as a published writer. His second novel, Rabbit, Run (1960), the first in a series of four novels and a novella featuring the American everyman Harry “Rabbit” Angstrom, was in danger of not appearing at all because of objections by his publishers, Alfred A Knopf in New York and Gollancz in London, to what was considered obscene language and descriptions.

In the ensuing struggles, the 28-year-old Updike showed impressive courage and forcefulness. On 2 July 1960, we find him writing to Victor Gollancz that “there is only one honourable and decent thing for me to do, which is to insist that the book be published as I wrote it or not at all”. And he added: “If I start fudging, I have no moral ground to stand on.” In the end, though, he had to give in, and accept the lawyers’ recommended changes. He did so with characteristic stoicism, writing to Gollancz that since “compromise is the only possible avenue … I will take it as gracefully as I can”.

Updike’s approach to the depiction and discussion of sex in his novels is strikingly brisk and commonsensical. He did not write to shock, much less to assert his masculinity. He simply did not see why the intimate doings between men and women – as a writer he had no interest in homosexuality – should not be described as accurately and with as much intensity as any other human interactions.

Nor does he seek to put heaven in a rage, or imagine for a moment that he might. He was in his middle years a serial and sometimes multiple adulterer, yet he held to his Episcopalian faith to the last, albeit with some lapses. In a letter to his “Dear Plowvillians” of 9 July 1960, he retails the censorship dispute over Rabbit, Run, and a little further on writes of how he has been helping out at his local Bible school – “very pleasant, except that it does take up the … morning”.

And then there are his women, in his life and in the work. Martin Amis observed of Updike that he was unembarrassable, on the page and in bed. In Couples (1968 – of course), his most successful and most lucrative novel – he was paid $400,000 for the rights to a film that never got made – the erotic content almost overwhelms the narrative. He was living at the time in Ipswich, a small town in Massachusetts, and the characters in the novel are so closely modelled on members of the Updike “set”, though he denied they were, that the libel lawyers were called in. Asked by a journalist for her reaction to the book, the author’s wife, Mary, said she felt as if she were choking on pubic hair.

At the heart of this volume we find the correspondence, from the first half of the 1970s, surrounding Updike’s separation and divorce from Mary, and his affair with and marriage to Martha – the biblical resonances of the names are almost too pat. These pages make for painful reading: Updike could be cruel – to Martha: “Mary’s body (her breasts!) would delight me still, if I could dissociate it from her pinched Unitarian soul …” – but in the main they are either pained, with Mary, or passionate, with Martha. And simultaneously, of course, he was having it off with other loves, old and new.

Are his books read now? Towards the end he made a glum self-assessment: “I have fallen to the status of an elderly duffer whose tales of suburban American sex are hopelessly yawnworthy period pieces.” Perhaps so; but he wrote such prose as to make the envious seraphim sigh.