With the advent of the internet, any topic we want to know about is instantly available with the touch of a smartphone button. With so much knowledge at our fingertips, what is there left for our brains to do? At a time when we seem to be stripping all value from the idea of knowing things—no need for math, no need for map reading, no need for memorisation—are we risking our ability to think? As we empty our minds, will we one day be incapable of thoughtfulness? Addressing these questions, Simon Winchester explores how humans have attained, stored, and disseminated knowledge. Studded with strange and fascinating details, Knowing What We Know is a deep dive into learning and the human mind. Throughout this fascinating tour, Winchester also forces us to ponder what rational humans are becoming.