
Recently voted the greatest fantasy of all time, after The Lord of the Rings and The Hobbit, Gene Wolfe's The Book of the New Sun is an extraordinary epic, set a million years in the future, on an Earth transformed in mysterious and wondrous ways, in a time when our present culture is no longer even a memory. Severian, the central character, is a torturer, exiled from his guild after falling in love with one of his victims, and journeying to the distant city of Thrax, armed with his ancient executioner's sword, Terminus Est. This edition contains the first four volumes of the series.
Book of the New Sun series by Gene Wolfe. (Highly recommended)
A Fire Upon the Deep (Either you like the Tines or the Skroderiders)
Tlön, Uqbar, Orbis Tertius by Jorge Borges (Is reality imbued with our ideas?)
Conan the Barbarian by Robert E. Howard (Not unlike "the Greeks" of modern fic)
John Carter of Mars by Edgar Rice Burroughs (perhaps the first true modern fic)
Understand by Ted Chiang (Most of his short stories are good, or provoking)
Xeethra and the Zothique Cycle by Clark Ashton Smith
The Dying Earth by Jack Vance
For the ultimate in non-basic vocab, try Gene Wolfe's Book of the New Sun.
The English translation of Metro 2033 is amazing. You can feel the stylistic differences originating in the Russian language, and it's a very evocative horror story with slightly longer sentences and richer language than ordinary books.
Both the Babel books and Metro 2033 (especially) were inspirations for me, writing my novel. And Wolfe is one of my literary heroes, one of the most amazing writers I have ever read. Every one of his novels is rewarding, often through not just language but complexity of plot and narrator. He uses unreliable narrators a lot; beautifully, in one of his series the narrator has amnesia and cannot remember what occurred the previous day, so writes notes to himself. (Soldier of the Mist. Also rewarding once you figure out the name and location references.)
An older classic: Mervyn Peake's Titus Groan is extraordinary in language, but also in the rhythm of sentences. Definitely one written to be read with a voice, not just internally.
Perdido Street Station by China Mieville has dense prose. Wonderful book, very rewarding to read.
Books have the potential to better the mind, but they don't do so simply by being written words. The books must be of a certain artistic caliber. The push to get people reading in general cannot be the end goal. The end goal is to get people to read quality books, to better the mind, affirm life, practice empathy, experience pathos, feel the grace of God. Too many forget this is the end goal and just think reading words on paper is somehow intrinsically a noble endeavor.
I think the common advice to get people into books is wrong and misses the point. "Find a fun trashy book and just read it" is maybe not productive advice unless attention rehabilitation is needed. Sure, some of those people might eventually stumble upon a good book, but advice can be much more efficient than that.
Here's what I would recommend to a burgeoning reader: There are many easy and fun books that have artistic merit; read those. Find them via Booktok lists from pretentious looking people, or common school reading lists, or wherever; generally only read things you have heard of or that you saw on a list somewhere; don't randomly pick off the shelf. Teenager classics like 1984, Book of the New Sun, Kafka on the Shore, American Psycho, Lord of the Rings are fun and easy reads that have meat on the bone. Ignore the airport novel and anything published recently. The average book has the same lack of value as the average TV show, just less entertaining, more boring, and more effortful to experience. Why would you waste time and effort consuming boring, less entertaining media when the phone and the TV are right there? But when you find good books, there is no replacement; you are doing an entirely different thing than mindlessly entertaining yourself. That is what we're trying to do.
(You can see it for yourself in all it's glory here: https://www.wholeearth.info/p/the-next-whole-earth-catalog-f... )
Other than that I'd have to say the Tao Te Ching.
(The best fiction book I've read is almost certainly "The Book of the New Sun" by Gene Wolfe. It's in the league of Tolkien and Dune.)
