Hans Rosling, the Swedish physician and statistician whose TED talks made data visualization famous, wrote this book in the final years before his death from pancreatic cancer. With his son Ola and daughter-in-law Anna, he identifies ten instincts that distort our worldview, causing even highly educated people to get basic questions about global development systematically wrong. When tested, most people believe the world is poorer, sicker, and more dangerous than it actually is. Rosling attributes this to hardwired cognitive biases that served our ancestors but mislead us now: the gap instinct that sees only extremes, the negativity instinct that notices bad news, the fear instinct that overweights dramatic risks. The book provides tools for thinking more clearly, using vivid examples and the interactive graphics Rosling pioneered. He documents genuine progress in global health, education, and poverty reduction without denying the serious challenges that remain. Rosling's combination of rigor and humor, his willingness to mock his own earlier misconceptions, makes the medicine go down. This is a book about epistemology disguised as a book about development, showing readers how to update their mental model of the world.