The Three Stigmata of Palmer Eldritch by Philip K Dick (1965)

In “The Three Stigmata of Palmer Eldritch,” Earth is suffering from global warming so much that it's dangerous to pause too long while walking from the air-conditioned building to the thermally insulated car.

To reduce overpopulation, the United Nations has instituted a draft to send colonists to live in permanent settlements on Mars, Venus and other planetoids. Life as a colonist on Mars is dismal, the only respite is to take the drug Can-D and participate in shared hallucinations where you can project yourself into a simulation of Earth. The simulations are based on a Barbie-like doll called Perky Pat, and an Earth-based economy has grown from selling the colonists both the Can-D drug as well as the accoutrements for the Perky Pat dollhouse that are needed for a realistic experience.

Meanwhile the famous entrepreneur Palmer Eldritch returns from his ten year trip to the Proxima system bringing with him a new drug called Chew-Z. Quite a bit of the book is spent exploring the possible effects of Can-D and Chew-Z, and the religious implications. Dick compares them to the Catholic doctrine of transubstantiation. Leo Bulero, CEO of Perky Pat Layouts, and his Pre-fash buyer Barney Mayerson attempt to stop Eldritch, working on various plans to kill him, or prevent the distribution of Chew-Z, but they fail. It turns out that Chew-Z may alter reality, as well as casting the user into hallucinatory states that are so realistic as to be indistinguishable from reality.

As Wikipedia mentions "The novel has an ambiguous ending." “Stigmata” is one of Dick’s most fascinating, frustrating, mind-bending novels. After years of approaching ideas in piecemeal, he’s decided to hit the reader with everything and the kitchen sink. If one were to map out common themes of PKD books, "Stigmata" would contain many of the most prominent: games, UN Rule, shared hallucinations, pre-cogs, satellites, drugs, time travel, religious experiences, Deus Ex Machina, Mars colonies, and even ceramics.

Surprisingly, ceramics and pottery show up as a theme in at least four of Dick's novels. In "The Cosmic Puppets" the children create animated miniature Golems from clay, releasing them into the world as spies or diminutive minions. And, there is of course "The Galactic Pot-Healer." In "Stigmata" Barney Mayerson's ex-wife Emily creates pots, and she and her new husband Richard hope to sell her designs to Perky Pat Layouts for miniaturization. If PP Layouts bought her pots, it would mean an instant channel for distribution and attention. If you include the jugs from the jug bands in The Simulacra, you can see that Dick has pots on his mind.

I think he uses clay or ashes as allusion to creation and destruction. The epigram to "Stigmata" takes the form of an inter-office memo at PP Layouts:

"I mean, after all; you have to consider we're only made out of dust. That's admittedly not much to go on and we shouldn't forget that. But even considering, I means it's a sort of bad beginning, we're not doing to bad. So I personally have faith that even in this lousy istuation we're faced with we can make it. you get me?"
"--from an interoffice audio-memo circulated to Pre-Fash level consultants at Perky Pat Layouts, Inc. dictated by leo Bulero immediately on his return from Mars."

The Perky Pat Layouts itself is an interesting concept. Here's Dick, in the early 60's, coming up with the idea for virtual worlds. I mean, Second Life and other virtual worlds are just a mapping of the Perky Pat Layouts onto cyberspace. Today Facebook acts like the PP Layouts, taking people's minds off toil and work and letting them engage others in a shared virtual hallucination --you're not actually physically with your friends, and they might not even be your friends.

Dick’s description of the Can-D experience is essentially a description of virtual sex:

“Her husband -- or his wife or both of them or everyone in the entire hovel -- could show up while he and Fran were in the state of translation. And their two bodies would be seated at proper distance one from the other; no wrong-doing could be observed, however prurient the observers were. Legally this had been ruled on: no co-habitation could be proved, and legal experts among the ruling UN authorities on Mars and the other colonies had tried -- and failed. While translated one could commit incest, murder, anything, and it remained from a juridicial standpoint a mere fantasy, an impotent wish only.”
Another character says “when we chew Can-D and leave our bodies we die. And by dying we lose the weight of --... Sin.”

Reading this, I wonder what Dick would make of the Internet? Would he see it as just so much gubble-gubble, or would it be a way to lose ourselves and meld with others?

Here’s from the inside flap of the first hardcover edition:

When Palmer Eldritch returned from a distant galaxy, he claimed he had brought a gift for mankind. It was a drug that would transport one into an illusory world. One could spend years in this other dimension and never lose a second of Earth time. Eldritch offered immortality, wish fulfillment...the powers over time and space. But he exacted a terrible price: he, Palmer Eldritch, would enter, control and be a god in everyone’s private universe - universe from which there was no escape, not even death.”

And from the back of the 1977 Manor Books paperback:

It was always Saturday.
You woke each morning with the comfortable feeling that you didn’t have to go to your job. Instead, you could climb into your brand-new Jaguar, pick up your girl and go to the beach.
Except that when you looked into your shaving mirror you saw a note tacked up, written in your own hand: “This is an illusion. Make good use of your time, buddy boy.”
Because the illusion wouldn’t last. And soon you would be back as an unwilling colonist on the dreary planet Mars.