In this case, let's suppose you are asked to write an essay on Alice Walker's "Beauty: When the Other Is the Self." Here, the assignment is to explore a theme contained in this complex and thoughtful autobiographical essay, which recounts the effects on Walker's self-image of a childhood accident that caused her to lose vision in one eye and to acquire an unsightly scar.
You decide to write on the theme of inner versus outer beauty. You can use clustering initially to open up the appearance of this theme in Walker's essay. You simply put "outer vs. inner beauty" in the middle oval and then brainstorm the instances of that theme in the essay. Further, more specific branching can then net more concrete examples. So far, we're doing the same kind of preliminary thinking we did with the W.H. example above.
Once that is done, however, cluster again, this time for discovery thinking, thinking which takes us beyond the confines of Walker's essay. Put "outer vs. inner beauty" back in the middle oval. Now brainstorm instances of this theme in other texts, other realms of experience. For example: you think of the fairy tale "Beauty and the Beast," which is also based on the same theme. Ditto with "Cinderella" (with its hundreds of cross-cultural
variants). You think of Cyrano de Bergerac. You remember that Tony Morrison wrote a book called The Bluest Eye that deals with a similar theme. How is it like or unlike Walker's essay? You remember enjoying Alice Walker's The Color Purple. To what extent does it connect thematically with the essay? What about American conceptions of beauty generally? How do they contrast with those in Africa? Asia? The Middle East? What about the economics of beauty? How does Freud address the issue of outer vs. inner beauty? Jung? What personal experience have you had that bears on the theme?
The purpose of these imaginative associations that clustering calls forth is not to destabilize your essay, which must focus primarily on the stuff of Walker's essay, but rather to enrich it. By establishing a link or two with parallel instances of your central theme, you can broaden your and our understanding of the essay. Or it may be that your teacher will encourage you to follow your discovery thinking into a full-fledged comparison.