Ulyssess, the quintessential modernist novel in English and one of the great landmarks of Irish culture, was first published in its entirety on February 2, 1922, James Joyce’s 40th birthday.

It was published in Paris, where Joyce was then living, to avoid prosecution for obscenity in Dublin, London or New York. At the time it was hailed by connoisseurs but greeted with revulsion by many, and for decades it was treated with suspicion by the fledgling Irish state.

Today, however, the centenary year is celebrated with anniversary editions, exhibitions, essay collections, academic lectures, Twitter bursts, newspaper reports, television and radio broadcasts and events at Irish embassies around the world.

What is the novel about?

It details the events of a single day in Dublin, Thursday, June 16, 1904 (historically, the day of Joyce’s first date with Nora Barnacle, his future wife, where, he says, she “made a man out of him. “).

The first three chapters follow Stephen Dedalus, Joyce’s fictional alter ego, who featured in his novel A Portrait of the Artist as a Young Man (1916). But most of the 18 chapters put the reader inside the head of Leopold Bloom, a Jewish publicity salesman who serves as something of an ordinary man.

Bloom eats breakfast, goes to a funeral, walks around town, looks up at women, and visits various pubs, all the while brooding over his wife Molly’s affair with Caddish Blazes Boylan. At the end of the evening, Bloom saves Stephen from a drunken fight with an English soldier, then sobers him up with a cup of cocoa. The novel ends with Molly’s sleeping thoughts.

So why is he called Ulysses?

Among other things, the book is based on the story of Homer Odyssey. Joyce preferred the Latin name Ulysses, admiring the character since reading Charles Lamb The Adventures of Odysseus as a child. (Joyce reportedly pronounced the name “Oolisays” and Dedalus as “Dead-alus”, not “Deed-alus”.)

Bloom is a modern Ulysses who travels Dublin rather than the Mediterranean. Stephen is a version of Telemachus, the son of Odysseus, while Molly is Odysseus’ wife, the faithful Penelope. Each chapter has a more or less playful parallel with an episode of The Odyssey. Instead of blinding a one-eyed giant with a sharpened stick, for example, Bloom brandishes a cigar while arguing with a stubborn man in a pub.

What’s so shocking about that?

Joyce’s focus on daily activities encompasses belching, nose pinching, farting, urination, defecation, menstruation, and sexual fantasies.

When a magazine printed the “Nausicaa” chapter, in which Bloom masturbates while ogling a girl on a beach, the resulting court case made Ulysses unissued in US until 1934; it was banned in Britain for 14 years. “Flagless obscenity and filth,” wrote Sir Archibald Bodkin, the Director of Public Prosecutions.

As well as running the gamut of swear words, the book begins with a character mocking the Catholic Mass. Irish nationalism and British imperialism are treated with similar disrespect. (When Joyce died in Zurich at the age of 58 in 1941, the Irish government refused to send a representative to her funeral.)

What did the critics say?

Ezra Pound and TS Eliot – whose poem The Waste Land was also published in 1922 – lined up to praise Ulysses. Eliot called it “a book to which we are all indebted and none of us can escape” (although Virginia Woolf complained that it was “illiterate” and “under-blooded”).

Joyce’s use of interior monologue—particularly the telegraphic, associative language of Bloom’s thoughts—offered fiction a new level of poetic compression and psychological depth. Some critics thought he had transformed the novel as Picasso had transformed painting.

Others, however, found it disconcerting and frustrating. The Quarterly Review described it as “literary Bolshevism… anti-Christian, chaotic, utterly amoral.”

What is its reputation today?

Anything but unassailable. It is considered “a novel to end all novels”, in the words of reviewer Harry Levin. Academics spend their entire professional lives unraveling its patterns and symbols. (“I put in so many riddles and puzzles that it will keep teachers busy for ages arguing over what I meant,” Joyce boasted.)

It is now a well-established feature of the Irish cultural industry. Dublin has a Ulysses trail, so fans can follow Bloom’s footsteps around town. The book has become a touchstone of Ireland’s relaxed, cosmopolitan modern identity. Unlike Eliot, Woolf, and Pound, Joyce was not drawn to anti-Semitism, snobbery, or fascism; he made his hero an ordinary man and a Jewish pacifist.

On the downside, it still has a fearsome reputation for difficulty; he can be said to have started a whole tradition of vast, unreadable novels aimed largely at male graduate students. Ulyssessaid John Carey, is a novel celebrating the life of an ordinary man that few ordinary men could read.

How hard is it to read?

The first few pages aren’t particularly difficult, once you get used to the quick jumps in and out of characters’ thoughts. But the third chapter – which begins with the words “Ineluctable Modality of the Visible” – is a bit of a speed bump, and as the book progresses Joyce throws more and more elaborate schemes at the reader.

One chapter parodies the complete history of English prose. Another – one of the best – is written in a question-and-answer format. It helps to have a copy of the text with notes or a guide handy. There can be, as Woolf noted, “long periods of intense boredom”.

But there are also plenty of great jokes, memorable characters, and some of the most moving and beautiful passages in the language. A much-loved 30-hour Irish radio adaptation from 1982 is available free on RTÉ’s website.