An unnamed narrator, a writer, notices an ad in his newspaper: “Teacher seeks pupil. Must have an earnest desire to save the world.” Although the narrator is initially dismissive of this ad, he goes to the office building mentioned in the ad, and is surprised to find that he is the only person who’s bothered to come. Inside, the narrator finds a fully-grown gorilla, sitting behind a glass window. In the room he also notices a poster, which says, “WITH MAN GONE, WILL THERE BE HOPE FOR GORILLA?”
To the narrator’s surprise, he can communicate with the gorilla simply by making eye contact with him. The gorilla says that he was born in Africa in the 1930s, kidnapped by humans, and taken to a circus. At the circus, a man named Mr. Sokolow purchased him. Sokolow gave him his name, Ishmael, taught him how to communicate telepathically, and gave him books to study. Eventually, Ishmael’s intelligence and knowledge far outstripped Sokolow’s. When this became obvious, Sokolow asked Ishmael to tutor his daughter, Rachel. Although Ishmael did so for many years, he reports that she never learned his most important lessons—lessons which he’ll try to pass on to the narrator now. Ishmael concludes his life story by explaining that after Mr. Sokolow died, his widow, Mrs. Sokolow, fought to keep Ishmael away from her home. As a result, Ishmael has ended up living in this building, supported with money from Rachel.
Ishmael asks the narrator if he feels like a prisoner, and the narrator answers that he does, but that he can’t put into words where this feeling comes from. Ishmael explains that the narrator is part of a culture, and as a result, he has been taught certain “stories”—explanations of the relationship between man, the world, and the gods—which are so pervasive that they’re invisible to him. Ishmael says that he will try to help the narrator understand these stories, and recognize why they’re false and misleading. As a basic lesson plan, Ishmael says that his project will be to show the narrator that human history is the history of two groups, the Takers and the Leavers, who enact two radically different stories about man, the world, and the gods. Takers, according to Ishmael, are the humans who developed agriculture and civilization—the humans who dominate the Earth to this day. Leavers (the Navajo, Bushmen, etc.), by contrast, are those who never adopt agricultural practices and ignore the supposed benefits of civilization.
During his first lesson, Ishmael asks the narrator to explain the one defining story of his culture. The narrator is unable to do so, and becomes impatient with Ishmael for forcing him to try. Eventually, using a tape recorder, he records himself talking about the history of the universe, the dawn of man, and the Agricultural Revolution. Ishmael shows the narrator that this version of the history of the world is a fiction: it favors the human race in an absurdly unrealistic way. The narrator realizes that Ishmael is right, but can’t get excited over this fact. Ishmael is disappointed with the narrator’s lack of enthusiasm.
In the second lesson, Ishmael and the narrator discuss the “middle” and “end” of the story of the Takers, as the Takers themselves see it. Takers believe that their inventions—agriculture, technology, etc.—have brought them great happiness and contentment, but they also believe that they must continue exploring new worlds in order to find new food and resources. At the same time, Takers believe that their technology and exploration inevitably cause death and destruction—furthermore, they believe that this is the case because human beings themselves are fundamentally flawed. This is a misinterpretation of the facts, Ishmael argues: while Taker culture and the enactment of Taker stories does lead to death and depression, human beings themselves are not inherently evil or sinful.
In subsequent lessons, Ishmael asks the narrator to explain the other stories that Taker culture believes. With much prompting, the narrator realizes that his culture—understood as Western culture, or industrialized culture—believes in its right to dominate the entire world. Humans, he argues, think of their exploration as a conquest—they’re literally waging war against the Earth. This, Ishmael argues, violates the one law of life: species should never wage war on one another. The inevitable result of humans’ violations of the laws of life, Ishmael concludes, is that the human species will go extinct. Though humans have tried to delay this from happening by producing more food, these measures are never fully successful: more productivity results in a larger population, canceling out any progress.
When he arrives for his next lesson, the narrator is surprised to find Ishmael sitting in the room, no longer behind the glass window. Ishmael talks to the narrator about the Hebrew Bible, arguing that it is actually a coded history of the human race, told from the perspective of the Leavers. When Adam eats from the tree of knowledge, Ishmael theorizes, he gains the knowledge of how to manipulate his environment and use agriculture to wage war on the Earth. The fact that this process is described as a “Fall” proves that the story was originally told by Leavers, long before it entered the Hebrew Bible. Ishmael goes on to also interpret the story of Cain and Abel as being about Takers and Leavers.
The narrator gets a visit from his uncle, falls behind on his deadlines, and gets a tooth removed. As a result, he abandons Ishmael for a week. When he returns, he’s surprised to find that Ishmael has left his building. The narrator does some research and learns that Mrs. Sokolow, whose name is Grace, has died, meaning that Ishmael no longer has a source of income to protect him from captivity. The narrator tracks Ishmael down to his new home: a traveling carnival. There, he finds Ishmael lying in a cage, from which he could easily escape if he wanted to. Ishmael ignores the narrator and eventually tells him to go away.
The next day, the narrator returns, and Ishmael reluctantly continues his lessons. A strange quality of Taker society, he explains, is that Takers both embrace history and reject history. Because they don’t have much “evidence” for how to behave, they’re always turning to prophets for advice—Jesus, Mohammed, Buddha, etc. Leavers, on the other hand, conduct themselves just as their ancestors three million years ago did, and so they have learned how to act based on trial and error. By ignoring the Leavers, Takers foolishly ignore the best evidence humanity has accumulated for how to act.
During the next lesson, the narrator bribes a carnival worker—the bribee—to speak with Ishmael after dark. Ishmael asks the narrator why he’s so interested in the ways of the Leavers, and the narrator answers that he thinks that the radical movements of the 1960s failed because although people know that Taker culture was wrong, they couldn’t see what “story” to replace it with. Satisfied with this answer, Ishmael conducts a complicated exercise with the narrator, in which he plays a Leaver, and the narrator plays a Taker. After this exercise, the narrator makes a breakthrough and realizes why Takers want to be Takers: they want to take control over their own destinies, rather than being at the mercy of the gods and the elements. There is no practical reason for being a Taker—only an abstract desire to be in control and to be different from the other animals of the Earth.
After this lesson, the narrator finds the man who runs the carnival, whose name is Art Owens. The narrator discusses buying Ishmael and agrees with Owens on a price, but then says that he’ll think about it. In the next lesson, the narrator asks Ishmael for advice about how to be a Leaver. Ishmael gives the narrator some goals: convince as many people as possible to abandon the ways of the Takers, and reject the idea that man’s role is to dominate the planet. Ishmael also makes the important point that the Leavers need not abandon agriculture altogether. Agriculture itself is a harmless enterprise—it’s only when agriculture becomes the way of the world, and when it’s used to wage war on the planet, that it breaks the laws of life. In general, Ishmael says, Leavers like the narrator must experiment with new methods for survival, “inventing” where they see fit.
The narrator leaves Ishmael to repair his car. While doing so, he decides to buy Ishmael and drive away, though he’s unsure where he’d go. When he returns to the carnival, he finds that Ishmael has died of pneumonia—the narrator hadn’t noticed that Ishmael had been getting sick. The bribee gives the narrator Ishmael’s possessions, including the poster the narrator saw when he first visited Ishmael. The narrator drives back to his home and studies the poster. He’s surprised to find that there’s another message on the back: “WITH GORILLA GONE, WILL THERE BE HOPE FOR MAN?”