It is a common truth that Joyce and Eliot fathered Modernism simultaneously, and that it happened in 1922. No sooner and no later. All other attempts were proofs of the same ideas floating in the air long before (from Laurence Sterne to Henry James, subversively with John Galsworthy, openly with Virginia Woolf, partly with Joseph Conrad, arguably with D. H. Lawrence). Some think it was more Joyce, others favour Eliot. Obviously, The Waste Land and Ulysses bear striking resemblances, from words to themes and moods, but — above all — there are similarities in craft. Human life has not changed basically so much over the centuries as to change its themes and existential moods. But, while man is essentially the same, the way in which he produces literature, the way in which human beings tell their stories becomes obsolete and is renewed from time to time. Which means the subject matter may not vary, even though the form does. It is the craft (the telling) which changes, not the told.
Because the style is the man, and the craft ultimately stands for the author, any change in craft is pretty important for whatever it is a particular author has to say. The most spectacular change took place when the story (which had previously been told in a commonly understood language) was suddenly wrapped, in 1922, in a language that made the readers sweat, a language that was ambiguous (lyrical), and encoded. Modernism being essentially a shift from prose to lyricism, Eliot might have engendered it. Eliot is the poet of Modernism and After. But Joyces intriguingly fertile narratives make one suspect that there may be much more to Modernism than lyricism.
When the radical changes in the 20th century took place (namely the theory of relativity and that of the relative psyche as seen by Freud, which led straight to the image of a world that self-destructs, and which we inhabit today), it seemed that Eliot was the man of the day. He was much more vocal than Joyce when it came to change. He chose to become the critic of change. Apparently.
Eliot came up with a radically different manner of writing poetry. He felt his mission was to refine the dialect of the tribe. He proceeded by invalidating the traditional poetic jargon: he ruined most decorous words, by quoting urbane poets and ridiculing their polish. He found aggressively ugly/vulgar images and tried his hand at forbidden words — only here Joyce had the upper hand. The unease was more obvious with Eliot than Joyce, because Joyce was endowed with a sense of humour and a verbal joy that grim Eliot lacked.
Eliot was also obsessed with the need to belong. After he had left Puritan America, he plunged into Anglo Catholicism in London. He became a fervent practitioner. Some of his most uninspired lines ever come from the church (The Rock, which, as a euphuism, we can call a failure). He risked his poetry for the sake of belonging. 
Joyce, on the other hand, left his native Ireland, left England altogether, and lived his life abroad. True, while Joyce was part of the establishment by birth, Eliot was coming from another universe, or so he often claimed, anyway. He consequently needed palpable proof that he was being accepted as a native Englishman, and considered part of the leading team of writers, of the gang in power. Eliot felt that belonging to English letters was a desirable possession, while Joyce could not wait to get away from it all. Belonging was the least of his concerns.
This being the case, it seems quite unlikely that Eliots repeated statements of change, novelty and difference should come from a solid, lifelong belief. As soon as he had his secure place in English letters (he even had a Nobel, eventually), he produced more and more texts to the effect of classicism. He recanted his youthful vehemence when he stated that he was sorry he had sent his critics on a wild goose chase (looking for reference embedded in his texts), and when he denounced in print his objective correlative and other famous labels he had once coined (To Criticize the Critic).
For quite a while I used to think Eliot was lucky to have been a poet, because it takes half an hour to read The Waste Land (Eliots good poetry amounts to no more than sixty pages all in all), while it takes a lifetime to finish Joyces Ulysses. I felt that — had another Joyce been born — the novel as a literary species would have died. I saw the good in Eliot and the bad in Joyce. I am now trying to amend, and look at things the other way round.
What changed my mind was a look at Eliots Ulysses, Order, and Myth (1922) [recte 1923]. He makes two significant statements there. First, when talking about classicism, he focusses on those who have won their own discipline in secret and without aid. He means himself, of course. Any act of writing is a discipline and a kind of order, a discipline and an order that depend on each individual writer. The same as with the objective correlative, with this sentence Eliot discovered America .
Eliots criticism was mainly self-expression, which any creation (criticism included), ultimately, though not exclusively, is. We know Eliots attitude to literature because, as I said earlier, he was more vocal than Joyce, he published literary criticism of his own. Joyce did not. Joyce left letters, openly all about himself. Eliot took a roundabout way: he managed to talk about himself while riding other authors.An example in point is Ulysses, Order and Myth. Eliot claims to be defending Joyce. He invokes a classical discipline to be acquired in secret by a selected few (only those, he says). Re praises Joyce for all the wrong reasons. He extols his mythical method of ordering the text. Actually, the farthest thing from Joyces mind was order. As a matter of fact, if anything, he was very keen on putting down to paper the very soul of disorder.
Eliots self-centred discourse makes Joyce a repository of things the poet would like critics/readers (many, many readers!) to notice (and acclaim) in himself. He is busy with his own struggle; after all, The Waste Land had just been published, had possibly already been called the hoax and the sacred cow of the century, a bejewelled toad, so much waste paper, a piece that passeth understanding, and so much more. That a critic, eapecially one who claims to be a poet before anything else, should have a hidden agenda is not unusual. Most authors (see David Lodge, for instance) have often turned to non- fictional  prose for one reason or another, and it has absolutely always ended in their supporting their own cause.
As if his idea of classicism had not been devious enough, Eliot added to it a few ridiculously self-assured words: the novel is a form which will no longer serve, it ‘ended with Flaubert and with James. The Eliot who made it a pattern not to make a statement has suddenly made a faux pas . He usually started in his criticism with an analysis of the terms he was to use in an essay, and once the words had been made perfectly unreliable, he would stop in delight, as if he had taught his readers a valuable lesson. His lesson was never to commit to an opinion. As he used to say, acknowledge the gift of a book before there has been time to read it: if you wait, you have to commit yourself to an opinion. And he would not do that.
In 1922 Eliot was thirty-four. If he had been older, he might have refrained from ruining the future of the novel in an imaginary script. I can understand the things he felt in the air, which he struggled with while writing. I can understand that it was the firm belief of the fateful year of change 1922 that lyricism was over and above everything else. He was not alone. Woolf, Conrad, even Galsworthy in his sketches got carried away by lyricism. Some lived to regret it, while others (like Galsworthy) stopped short just in time.
Eliots hidden statement had, in fact, something to do with the fact that Joyce also wrote poetry, made use of poetic techniques in his Ulysses, and was more resourceful with words than Eliot, but he did not stop there. He used poetry as a narrative tool, he made it a vehicle for the story. I wonder if Eliot ever forgave him that.
That Eliot hated the story in a poem (a bit of nice meat for the house-dog) is well known. He never dealt with the fact that he heavily relied on stories borrowed from others, which you are most imperiously commanded to find out, even though he complains that his Notes to The Waste Land led to no more than a wild goose chase. There is much ambiguity in his poetic status. Did he want to write an epic poem? Did he aim at a longer narrative in verse, which he never managed? He most certainly started out writing The Waste Land as a long diary. In the absence of narrative imagination, he fed on his own life, which, he felt, was full of incidents in his youth. He most certainly resented being unable to tell a story (just like Virginia Woolf). That is the immense tragedy and the only reason for the big change from pre-Modernism to Modernism: the author had lost his essential, indispensable gift of narration.
Looking at it this way, I am no longer sure Modernism was such a good idea, and it seems that Eliot felt the same. He compared his poem to Joyces novel, and felt that Joyce had escaped his predicament, had managed to hold on to the story. Under the circumstances, he being the un-narrative writer that he was, Eliot must have been at his wits end. Cornered against the wall, he shouted that the novel had died.
As we can see for ourselves in 2010, the novel is very much alive and novel has learned immensely from Joyce, while the poets are all building today on the now almost religious gesture of running away from Eliot … There are (besides personal, I suppose) literary reasons for which Eliot was for so long the opposite of a happy person. A writer with no sense of humour is – to say the least of it – a question mark. And Eliot was the most humourless author ever. 
Joyce, on the other hand, seemed to have been born to his name. He enjoyed words and stories and people and places, AND books – probably in that order. Eliot may have had this order in reverse. This must be the explanation of the fact that Eliot chose to promote himself while defending Joyce. As for Joyce, he had an outspokenly self-centred reaction to The Waste Land: “Hurry up, Joyce, its time!”