On reading The Goldfinch

Finally finished reading Donna Tartt's The Goldfinch, which took about two seasons. Normally I think an author who writes a piece 771 pages long is being self-indulgent, not reigning in the prose for their audience. But Tartt is one of my favorite authors, and not a big producer. I got excited when this FINALLY got released, because I loved The Secret History, and I ADORED The Little Friend. Yes, it's a little self-indulgent. But still damn good. And if I wrote like Tartt I'd indulge myself a little bit too.
The book is about a man who loses his mother (appropriate) in a freak accident and winds up with a priceless object that he's never able to let go of, namely "The Goldfinch," a painting by Carel Fabritus. It begins when he's a young boy and spans his entire life...like SH it's an epic, sprawling narrative. But her winding sentences and gorgeous, luxurious description of place kept me with it, except for a couple of stalling breaks around the time of my mom's dying and the holidays.

God how I wish I could do place like this (here, Amsterdam), in a way that captures sensory details and the narrator's distressed, drugged mental state:

"I took a wrong turn on the way to the hotel and for several hours wandered aimlessly, shops decorated with glass baubles and gray dream alleys with unpronounceable names, gilded Buddhas and Asian embroideries, old maps, old harpsichords, cloudy cigar-brown shops with crockery and goblets and antique Dresden jars. The sun had come out and there was something hard and bright by the canals, a breathable glitter. Gulls plunged and cried. A dog ran by with a live crab in its mouth. In my lightheadedness and fatigue, which made me feel drastically cut off from myself and as if I were observing it all at a remove, I walked past candy shops and shops with antique toys and Delft tiles from the 1800s, old mirrors and silver glinting in the rich, cognac-colored light, inlaid French cabinets and table in the French court style with garlanded carvings and veneerwork that would have made Hobie gasp with admiration - fact the entire foggy, friendly, cultivated city with its florists and bakeries and antiekhandels reminded me of Hobie, not just for its antique-crowded richness but because there was a Hobie-like wholesomeness to the place, like a children's picture book where aproned tradespeople swept the floors and tabby cats napped in sunny windows."

I mean breathable glitter? Cognac-colored? Come on. That's poetry.
This is my favorite kind of prose, too. Madman prose. But it's also about a secret object through which a story is revealed, which interests me as a teacher and scholar. It's also meant to be a written missive by the narrator, that is, he suggest that he is writing it as it goes. At the end, he claims to have kept a copies journal or notebook kind of thing consisting of letters to his dead mother, which accounts for the length and detail of the "memoir." Because I'm interested in diary-writing, this intrigues me. Is the painting the secret sacred object, or the book?

"...long obsessive homesick letters which have the tone of being written to a mother alive and anxiously waiting for news of me..."

What is the assumption of the diary writer about audience?

"...these epistles (dated and signed, in a careful hand, ready to be torn out of the notebook and mailed) alternating with miserable bursts of I Hate Everyone and I Wish I Was Dead, months grinding by with a disjointed scribble or two, B's house, haven't been to school in three days and it's Friday already, my life in haiku, I am in a state of semi-zombie, God we got so trashed last night like I whited out sort of, we played a game called Liar's Dice and ate cornflakes and breath mints for dinner."

Is it that a diary captures that state while we are in it, and forces a truthful reflection upon later reading? If the audience is dead and we alive, how is that like or unlike the dead author read by a surviving audience?