Symbolism, Imagery, Allegory
Atman is a concept found in Buddhism, Hinduism, and Jainism. Although the idea contains nuances within each religion, for our purposes here we can basically consider it to be translated as soul or self. But wait, we hear you say, didn't we already discuss the concepts similar in Buddhism and Hinduism in another section? Why are we separating this one out?
Answer: Zelazny does something particularly interesting with atman in the novel, something that requires a little side consideration in our discussion.
Of Auras and Origins
Atman comes into play right at the novel's beginning when Yama must use a satellite to fetch Sam from the great magnetic cloud around the planet like picking up a radio signal (1.120). Later, Yama gives a definition of the body-image (read: the self, or atman), which he describes as "electrical as well as chemical in nature" (3.471). Still later, Taraka refers to Sam's atman as a flame unaffiliated with language or ignorance (7.278-279).
There are other examples of the atman being explained differently, but you take our point: The novel can't come to any definitive conclusion on what the heck atman, or the soul, is. On the one hand, it's electrical and chemical, i.e. a natural part of our body. But on the other hand, it's a flame, something more intangible and supernatural about us.
All of these explanations are given the same weight in the novel, too, and accepted as accurate even if contradictory. Ultimately, the novel could be saying all of these explanations are equally valid. But it could also be arguing that they all leave holes in the true definition of atman. It kind of remains a mystery. Perhaps this is the point, though: Just like names don't really mean anything because they can't express the whole truth of a being (we discuss this in our convo about Sam in the "Characters" section), maybe the soul is unknowable.