Maria Popova traverses the border between life and death, chance and choice, chemistry and consciousness: what makes a body a person? What makes a planet a world? How do we safeguard our love of truth from our lust for power? What slakes our longings and what redeems our losses? Popova illuminates our various instruments of reckoning with these questions - our telescopes and our treatises, our postulates and our poems - through the intertwined lives, loves and legacies of visionaries both celebrated and side-lined by history, people born into the margins of their time and place who lived to write the future: Mary Shelley, Walt Whitman, Frederick Douglass, Fanny Wright. Woven throughout their stories are other threads - the decoding of the insulin molecule, the invention of the bicycle, how nature creates blue - which come together to create a rich tapestry of life's meaning; exploring what it is that makes life alive and worth living.