Letters mostly summon out of their writers a benign sense of self, the source of the distinctive charm and generosity the best of them have. Nothing is irrelevant to a letter, and anything can be left out. We paint our own portrait in friendly letters but in hostile ones we describe the recipient. Hurtful letters strike twice: first someone wrote those ugly words down and then posted them the same time as the gas bill.

Speech fades on the air but letters can’t be changed or erased. All this is true of the correspondence of Patrick White, who had a strong dash of self-loathing, and could be very tough on other people, but knew how to write the kind of letter that would illuminate your day. The White who inhabits these pages is generally a more benevolent figure than the one we discovered in David Marr’s biography, and a different writer from the author of The Aunt’s Story and The Tree of Man.

White didn’t think of his letters as literary documents, and loathed the idea of them being published after his death. ‘Letters are the devil, and I always hope that any I have written have been destroyed,’ he told his Viking publisher Marshall Best. Any? He wrote thousands, and can’t really have believed they would all crumble into dust after he did. Admittedly, he helped things along: in 1977 he asked his cousin Betty Withycombe to return the 400 letters he had written her over the years. They would help him, he said, with writing The Twyborn Affair. She obliged and White ultimately incinerated them.

Likewise, he burnt every letter he wrote to his mother, and to his partner of half a century, Manoly Lascaris.

Of course, huge numbers of his letters did survive, and White changed his mind about their publication, as he did about many things. David Marr has managed to unearth about 3,000 letters in all, and made use of about 600. Marr has cut ruthlessly but with finesse to create a book with narrative drive, and to complete the biographical record where new information has come to light. (Marr reveals for the first time, for instance, that the actor that White fell in love with in Melbourne in 1963 was Brian James, and prints three of the thirteen letters White wrote to him.) His footnotes, which constitute a kind of amiable Greek chorus to the text itself, are sharp, ample, and artfully cross-referenced. As the White era fades, readers will increasingly appreciate Marr’s thoroughness. Every now and then, I found myself wondering what he had left on the cutting-room floor, but this is the kind of question you wonder out of beguilement. The Letters is a whopping, Breugelish book, the natural companion to Marr’s biography, and of all White’s books closest in character to Flaws in the Glass, White’s 1981 autobiography.

White was a wonderful letter writer partly because he had ironed out of his character almost all the literary vanity that might have made him write with an eye on posterity. He once described himself as a ‘sensual and irritable human being’ and said on another occasion: ‘I am not of great interest as a person; I like to think my books are better than I’. His letters – gossipy, cranky, wise, funny – effortlessly express the everyday life he thought was humdrum but which he made palpable in his descriptions to his friends. They are full of light and air, of vivid detail recounted on the run without art or artifice. He wrote letters in moments of respite between nursing litters of puppies or bouts of cooking or sessions slaving away at his novels. Perhaps White was such a prolific and relaxed correspondent because for him letters retrieved the act of writing from the lonely agony of art. After Viking accepted The Tree of Man in 1954, White wrote to his publisher Ben Heubsch: ‘I don’t know whether other authors experience what I do: a feeling that they may be writing a secret language that nobody else will be able to interpret.’

In the midst of writing The Eye of the Storm, he confessed: ‘Every word is a stone to be lifted painfully.’ His letters aren’t like that at all. They were written fast, easily, and mostly to give their readers pleasure. The autobiography they describe is an incidental one of books, music, theatre, gardening, dinner parties, journeys, work. Letters weren’t for working out personal crises or confessing one’s innermost secrets. ‘How can one talk about anything so private as one’s “religion” and one’s God,’ he told a Swedish academic. Nor were they for discoursing about the intricacies of art. ‘I can’t talk about style,’ White wrote. ‘I only know I do what I do when I feel that has to be done.’ The temperamental, suffering artist is not much on display in this book, unless one includes grumbles about asthma or dentists or eye doctors.

A huge fraction of this book was written by the mature writer. The first forty years of his life is covered in one hundred pages or so. Once the novels started to pour out after the war, so too did the letters. But the turning point in this book, the moment where White becomes a profoundly interesting writer, comes earlier, in a diary he kept during the war, and which was only discovered after his death. The diary underlines how White’s stretch in Africa and the Middle East rescued him from becoming an English dilettante. Its prose has a hard bare, electric sensuality:

On the aerodrome the aircraft stand like big, waiting grasshoppers in the midday sun. Dust blows in the eyes. There are moments when it is not possible to see. Then the landscape returns, rock and dust, and a string of humped native cattle. An airman in a singlet hangs his washed shirt to dry on a rock.

White belonged to the last generation for whom it was optional whether or not be Australian, but his decision to embrace his fate and return after the war was of cultural as well as biographical importance. He was never able to shed his ambivalence about being an Australian writer in a country he needed like oxygen itself but also needed to despise. But he did massively prove that the contempt many creative Australians reflexively felt (and continue to feel) for their birthplace could co-exist with the highest achievement. Perhaps more than most, though, he needed a hostile environment to sting him into action and he did his best to perpetuate this sensation long after the Australian public had recognised his genius. In 1969, in the middle of writing The Vivisector, he declared, ‘I expect a lot of people will be furious and disgusted’, and it was the kind of thing he said while wrestling with every novel.

The hateful grouch of Martin Road, who really was furious and disgusted – with himself, with his discarded friends, his ‘piddling country’, almost everyone in fact except his ‘sweet reason’ Manoly Lascaris – emerges most strongly at the end of this book.

Letters like his diatribe to Ronald Reagan (‘Come on, cowboy’), reminded me of Ezra Pound’s more spectacular effusions. It’s hard not to draw the conclusion that in these ‘public’ letters White broke one of his cardinal rules of not believing his own publicity. As late as 1979 White could approvingly quote Philip Larkin saying ‘I don’t want to go around pretending to be myself’, but by the end White’s rage had become a grubby overcoat he loved to wrap around himself in public. My favourite letter, on the other hand, is the one he wrote in 1961 to the fifteen-year-old Philip Garland, the youngest child of his cousin Peggy, who had been born brain damaged. Only a kind of saint could write a letter like that and Marr rightly prints it entire.