For thirty years David G. Campbell has explored the Amazon, an enchanting terrain of forest and river that is home to the greatest diversity of plants and animals to have ever existed, anywhere at any time, during the four-billion-year history of life on Earth.

With great artistic flair, Campbell describes a journey up the Rio Moa, a remote tributary of the Amazon River, 2,800 miles from its mouth. Here he joins three old friends: Arito, a caiman hunter turned paleontologist; Tarzan, a street urchin brought up in a bordello; and Pimentel, a master canoe pilot. They travel together deep into the rainforest and set up camp in order to survey every woody plant on a two-hectare plot of land with about as many tree species as in all of North America.

Campbell introduces us to two remarkable women, Dona Cabocla, a widow who raised six children on that lonely frontier, and Dona Ausira, a Nokini Native American who is the last speaker of her tribe's ages-old language. These pioneers live in a land whose original inhabitants were wiped out by centuries of disease, slavery, and genocide, taking their traditions and languages with them. He explores the intimate relationship between the extinction of native language and the extirpation of biological diversity. "It's hard for a people to love a place that is not defined in words and thus cannot be understood. And it's easy to give away something for which there are no words, something you never knew existed."

In elegant prose that enchants and entrances, Campbell has written an elegy for the Amazon forest and its peoples-for what has become a land of ghosts.