Ubik is easily one of my favorite PKD novels: less lauded but more tightly composed than VALIS, it too makes pervasive but subtle use of Gnostic themes throughout. In his self-exegetical notes, Dick paired Ubik with The Three Stigmata of Palmer Eldritch as stories grounded in the mechanism of the Eucharist. (In Three Stigmata the Eucharist is averse or malign–a sort of interplanetary Black Mass.) The initial science-fictional concept in Ubik is that of the “moratorium,” a medico-funerary facility that arrests brain deterioration in fresh corpses, so that the “dead” can be milked for small amounts of further interaction with their survivors; all of which opens up the question of the subjective experience of such “death,” not to mention all death, and perhaps life as well.
The characters are unusually clear, lacking the amorphousness that Dick’s psychological approach often inflicts on his protagonists, and this feature may well have been a function of his onetime development of this story as a prospective film treatment. In my dream universe, David Cronenberg has already directed a production of Ubik!