From the acclaimed author of the New York Times bestseller On Trails comes a wondrous new journey through the wilds of nature and the gnarls of history, exploring how trees—from the mightiest sequoia to the tiniest bonsai—can teach us to grow wise.

One day, on a whim, Robert Moor set out to climb a tree near his home—unwittingly embarking on what would become a decade-long adventure of intellectual and spiritual transformation.

Pursuing the hidden wisdom of trees, he digs through forgotten archives, scales to the top of a giant sequoia with Sir David Attenborough, trudges through swamps in Papua to reach a treehouse-dwelling tribe of hunter-gatherers, and travels to a remote research camp in Tanzania, where he spends one very uncomfortable night sleeping in a chimpanzee nest. Galvanized by a radical new outlook on both our gnarled past and our ever-branching future, he ultimately falls in with a ragtag clan of climate activists risking everything to halt construction of an oil pipeline and save an old-growth forest.

Along the way, Moor learns the art of “treethinking,” which, he discovers, has the power to break open some of humanity’s oldest questions: What is the secret to truly growing old? How do we set down roots in an increasingly chaotic world? Can we ever learn to pursue our future in the farsighted, deeply entangled manner of an ancient forest?

A witty, relentlessly curious excursion through philosophy, history, and science, what begins as an ode to the miracle of trees blossoms into a joyous, daring, and fiercely hopeful effort to “arborize humanity.”