In "Sum," David Eagleman crafts a mesmerizing collection of forty tales, each a unique and thought-provoking vision of the afterlife. Eagleman, a neuroscientist by trade, weaves his deep understanding of the human psyche with a boundless imagination, presenting afterlife scenarios that range from the sublime to the startling. Imagine an eternity where you are a minor character in the dreams of others, or a cosmos where God is an indifferent microbe, or perhaps a reality where you confront all the versions of the person you could have become. These vignettes are not just explorations of the beyond but are mirrors reflecting our deepest fears, desires, and the quirks of our nature back at us. Eagleman's prose is both concise and evocative, turning what could be a mere speculative exercise into a profound inquiry into the human condition. "Sum" invites readers to ponder what it means to be alive, challenging our perceptions of identity, purpose, and the universe itself. Through its imaginative and often amusing tales, this collection offers a lens to view our own lives in a new light, making the familiar seem strange and the strange, eerily familiar. Eagleman's "Sum" is not just a book about the afterlife; it is a journey into the myriad possibilities of existence itself, leaving readers to wonder about the many different forms that life—and the lack thereof—might take.