The mediator Miss Gill expresses the main theme of Whirligig when she says, “We never know all the consequences of our acts. They reach into places we can’t see. And into the future, where no one can” (38). The powerful cause-and-effect relationship among the actions of individuals pervades Whirligig and informs its narrative structure as a whole. The death of Lea Zamora, itself a tragic and unintended consequence of Brent’s suicide attempt, serves as a catalyst for the action of the rest of the book. Likewise, Brent’s whirligigs affect strangers across the country. Alternating chapters of the book take place in the future and, as Miss Gill says, in places Brent cannot see. Steph, Anthony, Jenny, and the unnamed narrator of “Miami, Florida” each have significant encounters with Brent’s whirligigs. Brent reflects on this theme at the end of his journey when he thinks that Lea “set him in motion, motion that he was now transferring to others” (132). The mechanism of the whirligig, in which Brent “interlock[s] some of the propeller blades so that one would pass its motion to the others,” is itself a symbol of this concept of cause-and-affect (133).