Joyce is a stylistic sponge. From the time when he was very young, he consumed libraries' worth of books, and after reading one author or another he found that he could easily soak up their style and write in their own voice. That's actually one reason some of his early critics dismissed him as more of a mimic than an artist.
Joyce brings this skill to bear in Ulysses, where we are exposed to an enormous number of different styles within the covers of one book. In "Aeolus," we find Joyce pulling newspaper headlines from the speech-stream. In "Cyclops," we get 33 parodies of different styles of writing, each picking up on things the characters are speaking or thinking about in the scene. In "Nausicaa," Joyce satirizes sentimental literature for young girls, and in "Circe," he writes a surrealist play using the dreamscapes of Leopold Bloom and Stephen Dedalus. In "Ithaca," he employs the form of a catechism as he describes Stephen and Bloom having cocoa in Bloom's kitchen. But perhaps nothing is quite as impressive as "Oxen of the Sun," in which Joyce literally re-enacts the development of the English language from early translations of Latin verse to contemporary Dublin slang by moving fluidly from one style to another.
So what's the point of all the stylistic play? Well, Joyce had this idea that what you say is absolutely inseparable from how you say it. As Samuel Beckett wrote in his essay on Joyce (he was referring to Finnegan's Wake, but the comment is also applicable to Ulysses), "form is content, content is form." In a chapter like "Oxen of the Sun," where we get a number of different styles, Joyce, while still depicting the main scene in the maternity hospital, lets each style gravitate toward its natural subject matter. Thus, when he writes in the style of early Latin prose, he finds himself talking about the importance of procreation to the greatness of the nation. When he writes in the style of the 18th century satirist Junius, he finds himself talking about Bloom's hypocrisy in extremely scathing terms. When he writes in the sentimental style of Dickens, he praises the doctor's treatment of Mina Purefoy in hyperbolic terms. All of this, aside from being a virtuoso performance, is also a vast demonstration of the importance of style in determining content.
To knock the point home a bit harder, people generally think that you have this thing to express – say, the feelings that you are happy. Then you have to find the words to express that thing, and you could no doubt express it in a myriad of different ways. You could say "I am happy" or "Oh my God, I'm thrilled," or "Happiness has broken the dam of my despair" or "Right on" or "Happiness has come slanting into my thoughts like a ray of sunlight." Joyce's point is that you are saying different things with each of these statements. The first might convey contentment, the second might convey over-exuberance, the third might convey sentimentality, etc. In each case, the style isn't just a transparent medium by which you convey the thing that you are trying to say. Instead, the style is linked with what you are trying to say. Once again: how you say something determines what you can express.
So when Joyce isn't busy parodying other people's styles, his own tries to soak up the scene and the character's feeling as much as possible. If the characters are tired (as they are in "Eumaeus"), he makes the prose bored and simple. If Bloom is having an orgasm (as he does in "Nausicaa"), Joyce tries to make the words themselves come to a climax. If the characters dance (as they do in "Circe"), Joyce tries to make the language dance. One of our favorite examples, though, comes from "Lotus Eaters." Bloom wanders about Dublin, hungry and tired. As a cloud comes across the sky, he begins to think of the Dead Sea and falls into the depths of depression. His words become despairing, halting and hesitating, trying to build into complete sentences, but actually becoming more and more sparse and fragmented.
Check it out:
"A cloud began to cover the sun wholly slowly wholly. Grey. Far.No, not like that. A barren land, bare waste. Vulcanic lake, the dead sea: no fish, weedless, sunk deep in the earth. No wind would lift those waves, grey metal, poisonous foggy waters. Brimstone they called it raining down: the cities of the plain: Sodom, Gomorrah, Edom. All dead names. A dead sea in a dead land, grey and old. Old now. It bore the oldest, the first race. A bent hag crossed from Cassidy's clutching a noggin bottle by the neck. The oldest people. Wandered far away over all the earth, captivity to captivity, multiplying, dying, being born everywhere. It lay there now. Now it could bear no more. Dead: an old woman's: the grey sunken cunt of the world.Desolation." (5.59-61)
Up until now we've been emphasizing the variety of styles Joyce uses, but there's a particular style Joyce made famous and that has now become more or less inseparable from Ulysses: stream-of-consciousness (or interior monologue).
Joyce himself traced it to Édouard Dujardin in Les Lauriers sont coupes. He said, "In that book the reader finds himself established, from the first lines, in the thought of the principal personage, and the uninterrupted unrolling of that thought, replacing the usual form of narrative, conveys to us what this personage is doing or what is happening to him." In simpler terms, the interior monologue is a radically new way of capturing character's inner thoughts. Instead of writing in complete well-punctuated sentences, the goal is to more accurately capture the disjointed free-associating way that people think (as in the passage above). Five pages into "Telemachus," we are suddenly plunged into Stephen's inner thoughts without any sort of indication, and from that point on the book never really looks back. One of many effects of the style is that we get a greater intimacy with the thoughts of the novel's characters than we ever could have before. Joyce follows their twists and turns even into incoherence.
A last point on the style. Something we'll call the what factor. The point is that some of Joyce's sentences can be quite hard to process. You read the same sentence over and over again and you really have no idea what he's saying. Frustrating as these may be, you have to realize that as you struggle with the sentence, Joyce has forced you to bring much more attention to his words than you would have otherwise. Your eyes can't just move idly over the page in Ulysses. It's an active book, and as a reader you have to put in a great deal of effort in order to figure out what the sentence is saying. One way to think of these sentences is as Gordian knots, seemingly impenetrable riddles. But once you undo the knot and make the sentence go flat, you'll often find that the realization inside is pretty remarkable and probably couldn't have been communicated any other way.
If you don't believe us, here's one we'll help you along with. The lines come from "Ithaca:"
"From outrage (matrimony) to outrage (adultery) there arose nought but outrage (copulation) yet the matrimonial violator of the matrimonially violated had not been outraged by the adulterous violator of the adulterously violated." (17.292)
Later, the narrator comments on the "natural grammatical transition by inversion involving no alteration of sense" from the active to the passive voic". (17.294). Believe it or not these lines are moving toward Bloom's acceptance of Molly's affair. He has ceased to consider the situation as a perpetration, as a question of what Boylan did to Molly or what Molly did to Bloom. Instead, he has come to see it in terms of what was done to Molly, what was done to Bloom. As a result, Bloom manages not to be overcome by anger and jealousy because he can acknowledge that Molly was not outraged by what was done to her, that in fact she needed it and deeply enjoyed it. Coupled with the fact that he could not provide it for her, Bloom manages to achieve a mood of equanimity. It seems that Bloom's ability to reconcile himself to his wife's affair actually relies heavily on the grammatical form of the English language. A switch from the active to the passive voice (to an extent) allows him to accept Molly's adultery.