The novel examines the hidden cultural biases driving modern civilization and explores themes of ethics, sustainability, and global catastrophe.

Largely framed as a Socratic conversation between two characters,[1] Ishmael aims to expose that several widely accepted assumptions of modern society, such as human supremacy, are actually cultural myths that produce catastrophic consequences for humankind and the environment.

Quinn also details how he arrived at the ideas behind Ishmael in his 1994 autobiography, Providence: The Story of a Fifty-Year Vision Quest.

[3] The nameless narrator and protagonist thus begins his story, telling how he first reacted to this ad with scorn because of the absurdity of "wanting to save the world", a notion he feels that he once naïvely embraced himself as an adolescent during the counterculture movement of the 1960s.

Ishmael's life began in the African wilderness, though he was captured at a young age and has lived mostly in a zoo and a menagerie (before living permanently in a private residence), which caused Ishmael to start thinking about ideas that he never would have thought about in the wild, including self-awareness, human language and culture, and what he refers to as the subject he specifically teaches: "captivity".

[3] The narrator admits to Ishmael that he has a vague notion of living in some sort of cultural captivity and being lied to in some way by society, but he cannot articulate these feelings fully.

If Adam ("humanity") were to eat from this tree, he might think that he gained the gods' wisdom (without this actually happening) and consequently destroy the world and himself through his arrogance.

Ishmael finishes his education with the student by saying that, in order for humanity to survive, Takers must relinquish their arrogant vision in favor of the Leaver humility in knowing that they do not possess any god-like knowledge of some "one right way to live".

"[9] Ishmael proposes that the story of Genesis was written by the Semites and later adapted to work within Hebrew, Christian and Muslim belief structures.

As they were driven further into the Arabian peninsula, the Semites became isolated from other herding cultures and, according to Ishmael, illustrated their plight through oral history, which was later adopted into the Hebrew book of Genesis.

Ishmael explains that the Fall of Adam represents the belief that, once mankind usurps this responsibility—historically decided through natural ecology (i.e. food chains)—that humankind will perish.

He cites as fulfillment of this prophecy contemporary environmental crises such as endangered or extinct species, global warming, and modern mental illnesses.