Barker's vivid imagination, bolstered by his naturally philosophical bent, leads him into any number of thematic concerns in the course of his fiction. Two areas of recurring emphasis are apparent, however. The first of these, and the one which the author himself has been most prone to stress in public discussions of his work, involves the concept of fundamental transformation as the result of an intense, revelatory experience, something which in Barker's narratives seems to come close to the notion of epiphany as articulated in the fiction of James Joyce.

People, he says, are given a moment of revelation, which, I think, is just about the most important thing in the world — moments when they see themselves in relation to the imaginative elements which have erupted into their lives.

What separates these moments of revelation and transformation from the epiphanies of Joyce — and those of just about anyone else, for that matter — is, of course, their radically different bias: in Barker, such experiences are terrifying, gruesome, and not infrequently fatal. If the latter seems at first absurd, Barker takes considerable pains to make his point clear: even in death his characters are frequently better off than they were in life. An excellent case in point might be the story "Sex, Death and Starshine" (Volume I), wherein a mediocre acting troupe attempting to stage a production of Shakespeare's Twelfth Night (c.1600- 1601) is confronted by the disgusted and angry ghosts (zombies, actually) of theater audiences past. Faced with a challenge of such unprecedented magnitude, the troupe rises above its innate mediocrity to stage its best performance ever, upon the conclusion of which the theater catches fire and destroys the performers in the ensuing conflagration. Reassembled beyond the pale, the now-dead cast forms an inspired zombie troupe which plays for highly appreciative dead audiences throughout the country. Like the acting troupe in "Sex, Death and Starshine," the central characters in much of Barker's fiction are losers of one sort or another, and it is only through their confrontation with extremity, whether it leaves them whole, maimed, or even dead, that they achieve their true spiritual potential.

The second area of recurring thematic emphasis in Barker's work is somewhat difficult to articulate precisely, but seems to involve the concept of a necessary symbiotic relationship between humanity and what might be construed as its obverse, all inhuman but nonetheless sentient elements of creation, be they spirits, demons, monsters, or whatever else the imagination is capable of conjuring up. A significant number of these stories involve human contact with agents of Hell, as, for instance, in "The Yattering and Jack" (Volume I), a wonderful instance of black comedy in which a totally incompetent apprentice demon, sent from Hell to torment a man in an effort to win his soul, bungles the job horribly and is eventually enslaved by his intended victim. "Hell's Event" (Volume II) postulates the insertion of a demon in runner's clothing into a well-known marathon event with, again, the obvious objective of winning souls, while "The Last Illusion" (Volume VI), a decidedly offbeat Faust variant, involves the ultimately futile attempts of Hell's agents to salvage a body needed to balance their account. Interestingly enough, in all stories where the relationship and ultimate confrontation is between humans and agents of a conventional Hell, the demons are the ones thwarted or subjugated. This may also be the case in confrontations with certain other nonhuman entities, such as that found in "Rawhead Rex" (Volume III), wherein an unspeakably grotesque monster, which may be the result of a sort of Jungian mythic dread made manifest, is ultimately defeated through the efforts of a character who discovers its fatal weakness. More often than not, however, when humans battle the nonhuman (excepting agents of a conventional Hell), it is the humans who find themselves in positions of subservience and subjugation, although ironically their new circumstances may lead them to heightened states of consciousness and self-realization. This, in one form or another, would seem to form the thematic basis of such stories as "The Midnight Meat Train" (Volume I), "Pig Blood Blues" (Volume I), "Scapegoats" (Volume III), "Human Remains" (Volume III), "The Inhuman Condition" (Volume IV), "The Forbidden" (Volume V), "The Madonna" (Volume V), "In The Flesh" (Volume V), and "The Life of Death" (Volume VI).