India, Sept. 17 -- Writer and naturalist-explorer Robert Macfarlane's river journey begins at a modest but rare chalk stream (rivers arising from chalk bedrock) near Cambridge, where he is a professor. He is out with his young son Will, who questions him about the title of the book he is working on. "It's called Is a River Alive?" says Macfarlane. "Duh Dad," is the child's immediate response, "It will be short book then, for the answer is yes."

His instinctive innocent belief in the aliveness of rivers is echoed in ancient indigenous 'languages of animacy', which recognise the personhood of both humans and non-humans, reaffirming our kinship with the natural world. Macfarlane is more seasoned and knows this question to be political, if n...