What Does the Italicized Text Mean

What does the italicized text mean?
Dear Professor Hamblin,
Can you help me to understand Faulkner's punctuation use and style; specifically the use if the semicolon and the use of italicized sections. I think I'm getting the hang of his use of "lack of punctuation" in some sections—he wants us to hear "thoughts" as they come in and out of ones mind; which most often are not complete and "neat" sentences. But the specific use of the semicolon and the italicized sections are baffling me; I want to understand his intention by the use of this form.
— jfernand
Dear jfernand,
As you note, stream-of-consciousness narration seeks to portray a character's seemingly random and chaotic thoughts before they have been censored, organized, and, yes, punctuated by intentional acts of the conscious mind. What is important to recognize is that the ordinary free-flowing process of consciousness we all experience in our daily lives as ideas, images, sounds, and memories that float in and out of our minds is akin to, but not identical with, an author's use of the stream-of-consciousness narration. The author wants to create the impression of randomness and spontaneity that we all know and experience, but in actuality what we are reading is a deliberately constructed text (not at all what we call "free writing") that has been shaped and arranged and focused in a very precise and controlled (that is, artistic) way to create the effects the author wants to achieve in the story. As readers we think that we are following a character's thoughts (really, we know better but we are willing for the moment to suspend disbelief and play the author's game), when in actual fact we are tracing the author's selection, arrangement, and presentation of those thoughts. It's great sleight-of-mind magic, and Faulkner is one of the very best of the magicians playing the circuit. We see this trick masterfully performed in As I Lay Dying, but the technique is carried to even greater heights of virtuosity (in fact, to near perfection) in The Sound and the Fury.
Faulkner's use of italics in As I Lay Dying assists the reader (at least occasionally and somewhat) in sorting through and better comprehending the respective character's stream of thought. The italics function in a variety of ways. Sometimes, as in the chapter in which Darl narrates Addie's death (see pages 49–51) or Tull's account of the activities surrounding the funeral (see pages 90–92), they alert the reader to shifts in time or place or focus. At other times, as in the Dewey Dell chapter beginning on page 120, they are employed to suggest different layers of thought within a character's consciousness: for example, those thoughts that might be said to lie at the top of the mind and are very close to, and in some ways hardly distinguishable from, speech; and those that lie deeper, buried from view, too private and secret to be shared not just with the world but even with one's conscious self. At still other times, as in Darl's description of Jewel's behavior at Armstid's house (pages 180–183) or Vardaman's last speech (pages 249–252), the italics highlight a word or phrase for special emphasis, much like the refrain of a song or poem.
As readers we are grateful for these signpost italics that announce shifts in the narrative; but the problem is, Faulkner is not consistent in such usage. More on italicized text >

Dear jfernand,
Sometimes the place or focus or time period shifts with no italics to alert the reader to the change. Note for example, the three distinct sections of the second Darl monologue (pages 10–13). Anse and Tull are sitting on the back porch, and Darl walks past to get a drink from the water bucket. "Where's Jewel?" Anse asks, but before we have Darl's answer, we read a flashback from Darl's youth (resulting from an association brought into his mind by the taste of the water, much like the taste of teacakes brings childhood memories flooding into the narrator's mind in Proust's Remembrance of Things Past). Then, finishing his drink, Darl answers his father's question: "Down to the barn." Again an association of ideas takes Darl to another place (though in this instance not a different time) as the word "barn" leads to an imagined (some would say clairvoyant) view of Jewel in the pasture and barn with his horse. Faulkner may have felt that the associative links in this section supply clear enough transitions that the reader needs no further aid, and indeed that is the case. But my point is that sometimes Faulkner uses italics to signal shifts, and sometimes he doesn't. Readers quickly discover that his only consistency in this matter is his inconsistency. It would appear that Faulkner feels that if he occasionally alerts the reader to these narrative shifts, there is no need for the italics to be employed in every particular instance.
But the use of any italics at all serves to remind the reader that there is a controlling mind behind the characters' minds, and that mind is the author's. I noted in my lecture, "My Mother Is a Fish," as well as in another post in Q&A, that the "Faulknerese" that Faulkner sometimes has his narrators speak and think is out of character, highly inappropriate for the speaker and context and thus counterproductive to the illusion that the character and not the author is telling the story. This point is highly significant. Ever since the 19th century realist Gustave Flaubert established (and demonstrated so masterfully in Madame Bovary) the literary dictum that "The author in his work should be like God in the universe: everywhere present, but nowhere visible," writers have sought ways to "disappear" from their texts. Some choose to emulate Flaubert by adopting an objective, pictorial style devoid of any editorializing or interpretation; others replace omniscience with first-person narrators. Faulkner shows the influence of this tradition: he makes extensive use of character narrators, and he eschews didacticism (though several of his characters do not); yet he seems not at all interested in completely withdrawing from his text. His use of italics is just one more way that he calls the reader's attention to his presence.
Purists who believe in following the rules laid out in literary handbooks find Faulkner's intrusions illogical and even inartistic, like a playwright, perhaps, who keeps rushing onto the stage in the middle of his play and calling attention to himself. Others of us see him as a writer who boldly challenges the accepted norm, takes enormous chances, and invents new forms—in short, a literary genius.
— Professor Hamblin