At the beginning of Why Fish Don’t Exist, Lulu Miller invites the reader to contemplate the person they love the most and to remember that “Chaos will get them” (3). A key theme in the book is that chaos is an inevitable part of existence. Early on, Miller experiences this as a negative fact: an inescapable force that “will rot your plants and kill your dog and rust your bike” (3). But by the end of the book, Miller comes to see chaos in a different way, as the necessary element of uncertainty in existence that brings change, both good and bad.

Chaos appears early on in the life of David Starr Jordan. As a child, his beloved brother Rufus was killed by typhus—an eruption of chaos. In the aftermath, Jordan sought order with even greater enthusiasm. Miller describes Jordan’s journals as suddenly exploding with color, as Jordan sought to capture and categorize existence. Jordan would go on to pursue this passion on an increasingly influential scale, first at Penikese Island, where he caught the attention of Louis Agassiz—a naturalist who believed a divine hierarchy existed in the apparent chaos of nature—and then in his own work, collecting and naming fish specimens across the United States and in the Pacific Ocean.