Science fiction is one of the best genres for complex, introspective examinations of human nature. Although ostensibly concerned with the future of humanity and all the technological possibilities that can come with it, sci-fi is, at its core, about our ever-changing relationship with the world around us. The genre thrives on studies about the human psyche clashing against accelerated change, and how we as a species evolve as a consequence.

No book better explores these thematic concerns than David Mitchell‘s 2004 masterpiece Cloud Atlas. The ambitious and sprawling novel tells a series of stories across millennia, balancing both historical fiction and metafiction to produce one of the most original and wholly distinct works of the new millennium. Among its many strengths, Cloud Atlas also has what could be the best final line in modern sci-fi, a deceptively simple but no less powerful sentiment that perfectly encapsulates the book’s themes and sci-fi’s larger concern with human nature.

What Is ‘Cloud Atlas’ About?

Cloud Atlas has a singular structure, composed of six distinct stories, each one experienced somehow by the protagonist of the next one. The first five stories appear chronologically and end in a cliffhanger, leading to a self-contained sixth story set in a post-apocalyptic future. From there, each of the original stories picks up where it left off in reverse chronological order.

The five stories are: “The Pacific Journal of Adam Ewing,” about an American lawyer suffering from a mysterious poisoning during his voyage throughout the Pacific; “Letters from Zedelghem,” about Robert Frobisher, a struggling composer entering a complex arrangement with aging composer Vyvyan Ayrs; “Half-Lives: The First Luisa Rey Mystery,” about journalist Luisa Rey’s investigation into corruption and targeted assassination at the HYDRA nuclear plant; “The Gasthly Ordeal of Timothy Cavendish,” about an elderly book publisher who is tricked into committing himself to a brutal nursing home; and “An Orison of Sonmi-451,” about a clone who joins a rebellion against the state’s corporate culture. The central sixth story, “Sloosha’s Crossin’ an’ Evrythin’ After,” is set in a post-apocalyptic Earth and follows a tribal man and a woman from an advanced society as they make their way to the ruins of the Mauna Kea Observatories to learn a hidden truth.

Cloud Atlas has often received rave reviews, with praise going to its bold and grand narrative, structure, character work, worldbuilding, and thematic concerns. Criticisms often highlight how the book’s reach far exceeds its grasp and how it can feel incomplete in its ambitions. A film adaptation came out in 2012, co-written and co-directed by the Wachowskis and Tom Tykwer, starring an ensemble cast including Oscar winners Tom Hanks, Halle Berry, and Jim Broadbent, alongside Ben Whishaw, Hugh Grant, Hugo Weaving, Jim Sturgess, and Doona Bae. The film is a solid translation of a novel once thought to be unfilmmable, even if some of its creative choices are a bit hard to accept.

What Is ‘Cloud Atlas’ Final Line?

Because of the book’s reverse chronological approach, the narrative ends with the second part of “The Pacific Journal of Adam Ewing.” Set in the mid-18th century, the story mainly centers on the titular character’s awakening to the injustices around him, first by witnessing the brutalization of a Moriori man named Autua, whom he helps secure work aboard the ship en route to Hawaii. Once Ewing discovers that he is being poisoned by his presumed friend, Dr. Henry Goose, he is too weak to stop it or defend himself before being saved by Autua. Realizing he owes his life to Autua, Ewing decides to join the abolitionist movement.

Reuniting with his wife and her family, Ewing declares his ambitions. His pro-slavery father-in-law dismisses the idea of abolition, claiming that whatever efforts he can actually muster will ultimately amount to nothing, just “a single drop in a limitless ocean.” Proud and certain of his choice, and fully supported by his loving wife, Ewing fires back at the man, delivering one of the most beautifully constructed lines in modern sci-fi: “What is an ocean but a multitude of drops?” Thus, Cloud Atlas ends its larger-than-life, millennia-spanning narrative with a simple but potent and evergreen sentiment that perfectly sums up not only the book’s lofty ambitions but also captures one of the true purposes of sci-fi as a genre: to show the impact of one life across time and space.