Science fiction is often about exploring strange new worlds, seeking out new life and new civilization, and all that space jazz. This is sort of the case in Solaris, too; Kelvin goes out to a new strange planet and learns stuff.
The difference is that what Kelvin learns is mostly inside his head. Exploring out there just leads you back where you started, looking at yourself in a mirror—so when humans look out to the stars in Solaris, they're really looking into themselves. You can explore as much as you want, but the eyes that see the distant land, and the brain that processes it, are still your eyes and your brain. Adventure is a cramped and insular thing; the more you travel, the more you're stuck in the same place. Why bother even getting out of bed in the morning? (Yes, Solaris is a cheery book.)
The exploration of Solaris the planet is really the exploration of Solaris the book.
The exploration of Solaris the planet is really the exploration of God.
Sci-fi stories are filled with freaky foreign others—think: logical Vulcans with pointy ears, toothy drooling monsters exploding from your stomach, invading Martians blasting puny earthlings with heat rays—and they're all scary or weird or disturbing. In Solaris, though, the real scary, weird, disturbing thing is that there might not be any foreignness out there at all. The Vulcans, the aliens, the Martians—they're all just you. Which either means that the icky aliens are you, or you are them. Either way, it is confusing and unpleasant. And also, you have pointy ears.
Solaris shows that the alien is always the self.
Solaris shows that the self is always an alien.
Identity can mean who you are, your self, but it can also mean an identity—two things that are the same. So identity is both one and two—or more than that on Solaris, where people keep appearing out of thin air and replicating and splitting into several. How many people are there in Kelvin, anyway? How many people is Rheya? How many brains are floating around in that ocean? Rheya is part of Kelvin, and Kelvin is part of you, if you read him. In Solaris, it's hard to keep track of your self, and harder to figure if this self is in your head or out there, somewhere in space wearing a different dress… or the same one.
Rheya is the most real part of Kelvin.
The ocean is the most real part of Kelvin.
The characters in Solaris get a lot of alone time. The scientists all stay away from each other on the station, closeted with their visitors. And since their visitors are their own dreams, that means they're essentially sitting there by themselves with their thoughts. The ocean, too, is all by its lonesome with its waves and its mimoids, bubbling and sloshing. Sad lonely ocean brain. When you need to talk to Kelvin for company, well, you know you're really desperate. The guy isn't exactly a rollicking good time—which, of course you know, if you've read his analysis in the "Characters" section.
Contact in Solaris is isolation.
Contact in Solaris is the opposite of isolation.
If ghosts are memories of the dead, then Rheya is a ghost in Solaris; she's Kelvin's grief made flesh. She's a nightmare of guilt: He feels responsible for her suicide, so he hideously kills her, or watches her die, over and over. She's also a dream of happiness: The two of them go everywhere together, sleep together, tell each other they love each other, and plan for a future. And she's a bland recapitulation of a not very happy relationship: They're constantly arguing and talking about how they can't communicate.
Whether nightmare or dream or just memory, though, Kelvin can't get rid of her—which is how memories and grief work on earth, in space, or anywhere else humans may find themselves.
Nothing in Solaris really happens; it's all just Kelvin's dream about Rheya.
Memories in Solaris are more real and permanent than the people who remember them.
Solaris is supposedly science fiction, but since it isn't really interested in explaining any of the science very clearly, much of it can also be interpreted as mystical, or even religious. You have dead people resurrected; a vast, unknowable consciousness that is both outside and able to read your inmost thoughts; miracles and—when explorers are destroyed by the ocean structure—devastating natural disasters as acts of (some sort of) god.
At the end of the novel, Kelvin suggests that the ocean may be an imperfect god—but we don't know enough about it to figure out if it's imperfect or perfect. And, of course, its unknowable nature only makes it seem more divine.
Kelvin is in hell being punished for his sins.
The ocean answers prayers.
You'd think someone writing science fiction would like science. But not Lem. In Solaris, science instead often seems to be a joke. Scientists have theories about Solaris, and then the theories are shown not to work, and then they figure out new theories, and then those theories don't work either, and all the theories are equally nonsensical gibberish and in the end everyone just sort of gives up. Science is a silly, pompous endeavor, and it generates a lot of nonsense. Scientists think they have knowledge, and then the ocean kicks their butts and they whimper.
Have you checked out the "Genres" section yet? Now would totally be a good time to do that.
Lem respects scientists even though he doesn't respect science.
Kelvin respects scientists and science, but Lem doesn't seem to respect Kelvin.
In Solaris, dreams become reality, and the contents of the characters' heads crawl out of their brains and become real. This is upsetting. It also calls into question what is "real" in the first place. Is reality out there, agreed upon, like the ocean? Or is it also what you think about the ocean? (That it's a big old brain, for example.) If Rheya isn't real, it also seems to call into question whether Kelvin is real—and of course, he ultimately isn't since he's a character in a book. The book is a kind of puzzle, tossing up different versions of reality to watch them totter about or fall apart—much as the ocean does.
Nothing that happens to Kelvin is real.
Everything that happens to Kelvin is real.