Writing is a reflex of absence, an attempt to make contact with a distant, elusive reader. No one understood the tenuousness of the undertaking better than Samuel Beckett, whose hero in Malone Dies writes himself to death, and after sharpening his pencil at both ends is gratified to see that "my lead is not inexhaustible". But despite his scepticism about what he called "the making relation", Beckett was a loyal friend and a tireless letter writer.

Dublin with its dripping weather and teetotal Sundays depressed him, so he spent much of the 1930s in London, Paris, Hamburg and Berlin; as he wandered, letters kept him tethered to indispensable friends like the art historian Thomas McGreevy, his principal correspondent in these early years. Every message to McGreevy concludes with a plea for reciprocation: "Write soon" or: "Keep me in the current" or: "Hurry up back."

Beckett left 15,000 letters and his American editors seem determined to cram most of them, along with their own prattlingly pedantic commentary, into four bulbous volumes. This first instalment records the young man's fumbling efforts to make his way in the world. His shoe explodes on the Boul' Mich in Paris, reducing him to a Chaplinesque tramp; he pleads for review copies from snooty London literary editors and is wittily resilient when publishers reject More Pricks Than Kicks or Murphy. In one lodging house, he is tormented by neighbours with a raucous wireless and with saintly forbearance says: "I must put up with it." In another he is grateful for "a big big room with plenty of space to pace the masterpieces up & down" on a floor of linoleum that looks like "Braque seen from a great distance".

His first letter is addressed to his mentor, James Joyce, whom he served as a translator, researcher and general factotum throughout the decade. A long-suffering aside reports on "the usual drama" with Joyce, and he might be obliquely reflecting on his own submissiveness when he sneers at admirers who "would feel honoured if Joyce signed a piece of his used toilet paper".

The services rendered are not entirely selfless, since Beckett hopes to give his own career a "kick in the arse" by writing a homage to Finnegans Wake for a French magazine. Joyce at least responds with paternal solicitude when Beckett is stabbed in the chest by a crazed clochard and intervenes to secure him a private room at the hospital. Joyce's death in 1941 will surely be the traumatic event that starts the second volume.

When Beckett's father dies in 1933, speech is stifled. "I can't write about him," he touchingly tells McGreevy. "I can only walk the fields and climb the ditches after him." The death of his literary parent may turn out to have a different effect; only after being freed from Joyce's intimidating influence could Beckett find his own voice.

Writing from Dublin to McGreevy in France, he quotes Stephen Dedalus's recommendation of "silence, exile and cunning" as the tactics that help a young artist to survive. The mantra needs modifying in Beckett's case: his preference was for expulsion rather than exile, and he repeatedly describes his writing as the evacuation of bodily waste. Poems are pustular or else they explode from within him like spermatic missiles. When a journal accepts a few of these "turds from my central lavatory", he celebrates by turning the church's wrathful "dies irae" into a fluent, gushing "dies diarrhoeae". The "Beckett Bowel Books", he jokes, should be issued with samples of laxatives "to promote sales".

His literary criticism is succinctly sanitary, as when he points out that "T Eliot is toilet spelt backwards". In a crucial letter to McGreevy about "the deanthropomorphisation of the artist" - his need to escape from romantic confession, aspiring to the dehumanised austerity he found in the paintings of Cézanne - Beckett concludes by apologising for his "dégueulade". The word means a protracted puke: to write is to turn yourself inside out, voiding the body's contents.

Exiled from Ireland and from his native language, Joyce wrote Finnegans Wake in a punning, polyglot idiom of his own invention. Beckett has his own equivalent to this composite babble. As he travels, he is constantly translating, aware that any word is a dubious, untrustworthy translation of a feeling. The "sensation of taking root" disgusts him and makes him think of a malignant polyp; he deracinates himself by carefully standing aside from whatever language he happens to be using, like an alien intrigued and mystified by the dialect of the tribe.

He gets through the ordeal of Christmas and New Year in Ireland by giving the occasions their French and German names, Noel and Silvester. A letter written in German declares that it is "difficult, even pointless for me to write in formal English", asks permission "to violate a foreign language" and hopes for a futuristic "literature of the non-word".

Eventually, Beckett found that potentially silent medium in the theatre. In a play, action or inactivity matter as much or more than speech and one of his last theatrical experiments consists of a single exhaled breath that wordlessly gives up the ghost in a cry lasting 25 seconds.

As this volume ends, we are still waiting for Waiting for Godot. Tom Stoppard has said that he's hoping to stay alive until the rest of the collected edition is published; I'm not exactly holding my own breath, but there are clearly delights and discoveries in store.

The Letters of Samuel Beckett: Volume 1, 1929-1940
edited by Martha Dow Fehsenfeld and Lois More Overbeck
882pp, Cambridge, £30

This is the one we've been waiting for - apart, that is, from the rest of TS Eliot's letters (it's a scandal that, nearly half a century after his death, we have only one, grudging volume of those). Beckett was famously private, but that didn't stop him from writing an awful lot of letters.

His editors operate under greater difficulties than most, not only because of the breadth of allusion, and the allusive and elusive wordplay you might have expected between intimate and highly educated correspondents ("'nastorquemada nyles' has not been identified with certainty," say the editors, and I can't say I blame them), with some of the letters written in French and German, but also because he had absolutely shocking handwriting - bad enough for Beckett himself to apologise for what he called his "foul fist". In the general introduction, the editors quote one (unnamed) correspondent: "That never is Sam Beckett's handwriting. I can read every word." On the other hand they, and we, are particularly fortunate in that the majority of the letters here have been written to his best friend, Thomas McGreevy, whom he met when teaching at Ecole Normale Supérieure, and to whom he wrote in absolute candour and trust, as an intellectual equal and confidant. A correspondent like that is gold, and there are times when we wish we could see McGreevey's letters to Beckett, for to have delighted such an exacting critic must have taken some talent.

Here is the authentic early Beckettian tang, straight from the source, unmediated by artifice. He may always have been a verbal show-off but underneath the pyrotechnics lie real humour, real pain. "My dear Tom, Delighted to get your letter. Do write again. This life is terrible and I dont understand how it can be endured," he writes in 1930 from his parents' home in Cooldrinagh (errors of punctuation, spelling and grammar have been allowed to stand uncorrected). "I would like to live in a perpetual September," he writes in September 1935. "One does one's best to prefer Spring, in vain." One recalls the story about his comment, made many years later, to a friend who was with him watching cricket on a sunny day and who had just said, perhaps forgetting to whom he was talking, that it was the kind of day that made you glad to be alive; "I wouldn't go as far as that" was the (apocryphal) reply.

It was, he said, his long experience of failure that made him as a writer; here we see him under its first full cold blast. A friend of the Joyces, Nuala Costello, tells him that "you haven't a good word to say about anyone but the failures"; he notes that this is "quite the nicest thing anyone had said to me for a long time". Trying to sell his first novel, Dream of Fair to Middling Women, he writes: "The novel doesn't go. Shatton and Windup thought it was wonderful but they couldn't they simply could not. The Hogarth Private Lunatic Asylum rejected it the way Punch would. Cape was écouré in pipe and cardigan and his Aberdeen terrier agreed with him. Grayson has lost it or cleaned himself with it. Kick his balls off, they are all over 66 Curzon St, W.1." (I love the way we know exactly what he means when he says "cleaned himself".)

Beckett's strong language is one of the things that give the letters their pungency and drive; it is a testament also to the suppleness, rigour and strength of his writing that they don't seem in any way dated, unless a wide frame of cultural reference is these days in itself passé. (You wouldn't have guessed, perhaps, that the passage quoted above was written in 1932.) Even a scant acquaintance with his oeuvre will prepare you for the scatology of a proposed literary creation: "When I imagine I have a real 'twice round the pan and pointed at both ends' I'll offend you with its spiral on my soilman's shovel." The only surprise is that it's to a publisher - albeit one he was friendly with. (The sympathetic Charles Prentice of Shatton and Windup - sorry, Chatto & Windus - who published More Pricks Than Kicks despite the reservations of his colleagues. Expect to pay about £4,500 for a copy of this edition today.)

The selection is not complete. Try cross-referencing some of the more interesting letters mentioned in James Knowlson's biography, Damned to Fame, with those in this volume and you will often find yourself drawing blanks. At the beginning of December 1933, he writes to McGreevey that he is "de nouveau amouraché, fais la cour sans conviction" ("a little smitten again, and [I] court without conviction"); the letter to McGreevey in this volume dated 6/12/33, which has to be the one Knowlson mentions, doesn't have that line, but it does have an ellipsis in square brackets indicating a cut. Did they elide this passage because they were trying to spare someone's blushes? And whose? Beckett's, in the grave for two decades? Or - Knowlson's hunch, and, given the way Beckett writes to her elsewhere, I think he's right on the money - Nuala Costello's? She died in 1984 and is in no position to mind. There seems to be a similar reticence elsewhere. Where's the letter, undated, referred to by Knowlson as the source for Beckett's confession that he'd got so drunk the night before that he couldn't find his glasses the next morning? It's odd because, as should be apparent, the editors are not consistently prudish; I've mentioned some of his riper language (he contemplates losing his post at Trinity College, Dublin to "some charming little cunt of a gold medallist"), and we have this assessment, from Germany: "I saw more whores in Dresden, whores of the old school, any evening I felt so inclined, than in all the months since October and all the places since Hamburg put together. Sächsiger Stützwechsel!" The last two words, we are helpfully told, refer to the "Saxon support system . . . a pattern typical of Romanesque architecture in Saxony". Let's not say that the editors have been less than diligent in their work, although they could have got someone British to tell them Optrex not only was, but continues to be, "a commercial eye drop". (Beckett suffered terribly from, among an enormous number of other things, styes.)

But these are minor cavils. A complete edition would be several times longer and something has to be trimmed. And we do have plenty to be getting on with. The difference between Dream of Fair to Middling Women (1932) - a clotted, knotted piece of writing - and Murphy (1938) is considerable, in terms of technique. The period covered here is when Beckett came to grips with the style that was awaiting him, and in these letters you can see numerous episodes when he really begins to flex his muscles. His description of the kite flyers at the Round Pond is beautiful whether you are familiar with the relevant passage from Murphy or not. We learn, too, about his intellectual and aesthetic development - I was interested to note, for instance, how much space TS Eliot occupied in his internal landscape.

But what comes over most is Beckett's humanity. To those who have read the biographies this will not be news, but you can see now even more plainly that for all his diffidence, he was more thoroughly decent than you might have suspected. This, for instance, describing a fellow-lodger in a pension in Hamburg, is both charming and stylistically rewarding: "And there is an Irishman called Power, who has not been in Ireland, who was born in Gibraltar, whose home is in Peru, whose interests are in Spain & family in Marburg, whose family left Waterford, while the going was good, in the 18th century. He stood me lunch in a vegetarian restaurant."

One regrets the decisions (a) to omit any and all juvenilia (how many letters must he have written before the age of 23!), (b) to print the book on paper of such density that reading it makes some kind of lectern a necessity, and, as a consequence of this, (c) to make the book so expensive that the lay Beckett reader, so to call the non-academic one, will have to think very carefully about buying a copy. If they do, they won't regret it: there are treasures upon treasures here.

 This article was amended on Tuesday March 24 2009.