This review was first published in The Literary Review Issue 400 July 2012

Virginia Woolf detailed the 'rigours of composition' in Orlando: 'how he wrote and it seemed good; read and it seemed vile; corrected and tore up; cut out; put in; was in ecstasy; in despair; ... saw his book plain before him and it vanished'. These words could describe the forty-six-year existence of Tom Phillips's idiosyncratic and ever-evolving masterpiece, A Humument. Conceived in 1966, its first edition was delivered in 1973, since when there have been three revised editions. A shiny new fifth edition has just seen the light of day, both as a physical book and as an app for iPhone and iPad.

A Humument is not so much composed (to use Woolf's term) as de-composed and re-composed. On 5 November 1966, Phillips selected, at random, a copy of W H Mallock's 1892 novel, A Human Document. He read it and it seemed vile - he points out Mallock's anti-Semitism - but also intelligent, allusive and luxuriant. Inspired by John Cage and William Burroughs's experiments with chance and cut-up, Phillips set about Mallock's text. The arresting title was created by folding a page, concertinaing A Human Document into A Humument. The nominal hero, Bill Toge, conflates William Mallock's Christian name and four letters from 'together' (or 'altogether').

Phillips began to doctor the pages with images, both abstract and figurative. Early examples tended to be simple, geometric patterns with hints of colour. But as the fifth edition illustrates, Phillips's designs have become increasingly sophisticated, from a vivid self-portrait (alongside a photograph of Phillips playing cricket) to parodies of Blake, Picasso and Pop Art, to collages of Marvel comic strips, maps, and old postcards.

These designs interact with Mallock's similarly treated text. Phillips highlights (or rather, leaves exposed) short phrases or individual words in speech bubbles, which are joined via little rivulets. Visually, the effect is akin to surrealist satellite pictures of archipelagos, or viewing cell formations under a microscope. Verbally, it feels as though Burroughs, Joyce and Beckett are text messaging haikus back and forth: 'beautiful/last/random fragments of poetry/finding syllables,/the waters fall/the waves fall/musical./pencil murmuring'.

A Humument is both a collaboration and a collision: between language and the visual, and between Mallock and Phillips. There are times when A Human Document sounds eerily prescient about its future at Phillips's hands: 'a singular record, not only on account of its contents, but of the manner in which it seemed to be composed'. But the fun of first encountering A Humument is witnessing Phillips going against the grain of Mallock's stately Victorian prose. 'Hi poetic people', Phillips hollers on page 136, against a background of avid cinema-goers wearing 3-D glasses.

Nowhere is Phillips's impolite subversion more explicit than his excavations of sexual image and innuendo. Page 116 offers a convincing impression of Burroughs's Naked Lunch. Having introduced a 'pleasure district', Phillips fashions a baroque portrait of an artist as an orgasming man: 'Paul Veronese. He suddenly ejaculated, You know Veronese - above the sideboard. Up in the cupboard on the wall. On the contrary.' Page 244 becomes a phallic symbol: 'A living thing of ceaseless sliding/Watch a huge cylinder ... The burnished piston - rising and falling.' The pictorial backdrop is what Larkin described in 'Sunny Prestatyn' as a 'tuberous cock and balls'.

Larkin himself can be glimpsed on page 76, spliced with a clown. It is one of many verbal and visual allusions. Byron, Goethe and Keats are all snuck in. Donne's 'Batter my heart' runs the length of page 80. Page 254 soliloquises, 'Tomorrow and tomorrow and tomorrow', adding a fourth 'tomorrow' for luck. The most coherent allusion is page 366's homage to the finale of Ulysses. Having selected 'And I said yes yes I will yes', Phillips inserts a cheeky sigh ('Oh,/Ah') in the middle, and an 'end' to end. The page is a painted mosaic of what seems to be 'Algy' Swinburne's 'snot-green sea'.

These references draw attention to the fine lines between originality and allusion, chance and intention, reading and composition. 'Make it new', A Humument urges, somewhat ironically as Phillips ventriloquises Ezra Pound through W H Mallock. Where does this leave Phillips himself? Is he interpreter, editor or creator? Is he, as page 113 avers, an 'unauthor'? Is he simply a piss artist, playing a highly wrought game of fridge-magnet poetry without using a single original word? Then again, how many novels do use original words? Phillips himself would doubtless propose that A Humument does: 'ossib/dang,' sings page 113, 'anquil tomary'.

At a time when the physical book is being displaced by the virtual, A Humument reminds you what material reality can achieve: while the app is fun, it doesn't hold a candle to the experience of reading the real deal. The baton has already passed to Phillips's heirs: the splendid Visual Editions, who have published Adam Thirlwell's typographically challenging Kapow! and Jonathan Safran Foer's paper-cutting Tree of Codes. But clever as they are, Kapow! and Tree of Codes feel like vanity projects between the 'serious' business of Thirlwell and Foer's novels. A Humument has become Phillips's life's work, albeit in the most modest of ways: 'My little muse was/connect/connect'; 'To resume/narrative/lite'.

Longevity has lent the project gravity. This edition of A Humument strikes a persistent note of wistfulness. There are meditations on ageing - Phillips has just turned seventy-five - and yearning for things, people and places past. In lyrical mode, page 233 calls this 'The glimmering shores of yesterday receding'. Page 259 goes pop: Mallock does some karaoke, singing the Beatles' line 'I believe in yesterday'.

The book is how Phillips processes the world around him: page 4 highlights 'nine/eleven' against images of the World Trade Center attacks and allusions to Dante, Goya and King Kong. A Humument is also how Phillips processes his life, feelings and art: 'Fragments of poetry/fragments of my mind/its petal unfolding', he uncovers on page 159. 'Every day of my life is like a page.'

And while there is melancholy and fear, Tom Phillips has too much fun messing with Mallock to feel sorry for himself. 'Laughing amongst/colours', he writes on page 183: 'Only the word pictures the word/joy joy joy as plied words slipped into his heart like surprise and pleasure.' All humument life is truly here.

James Kidd is arts correspondent for the South China Morning Post