“Books, like landscapes, leave their marks in us,” Robert Macfarlane once wrote. “Certain books, though, like certain landscapes, stay with us even when we left them, changing not just our weathers but our climates.” Macfarlane’s writing has done this for us and for millions of readers. It has shifted our climates for the better, deepened our sympathies, expanded our understanding of and attention to our moral and physical landscapes, and reminded us of the stakes of being alive. In this episode, Macfarlane joins us to speak about his new book, Underland: A Deep Time Journey. In the book, Macfarlane explores how we humans shape value across expanses of “deep time” — geological time in which the units of measurement are eons and epochs, not days or years — and asks: Are we being good ancestors? “When viewed in deep time, things come alive that seemed inert,” he writes. “New responsibilities declare themselves. A conviviality of being leaps to mind and eye. The world becomes eerily various and vibrant again. Ice breathes. Rock has tides. Mountains ebb and flow. Stone pulses. We live on a restless earth.”