India, May 17 -- You have said you are "north-minded," drawn to high altitudes and latitudes, to snow, ice, and rock, to mountains. You debuted with Mountains of the Mind but then your trajectory descends and your latest book is on rivers. Why? Mountains and rivers live in an ancient dialectic; mountains lend their gravity to rivers, as it were, and rivers in return sharpen and cleave mountains. So, in a strange way, turning to rivers felt like coming home. I have always been drawn, as a writer, to the limitless terrain where nature meets culture; where the complex and eventually unmappable reciprocities of imagination and landscape shape one another, dynamically. Is A River Alive? asks its readers to imagine rivers as possessing lives, deaths and even rights, and to see what consequences flow from that, in terms of law, story, song and, of course, the aliveness of rivers themselves. I've never known a subject like this one -- so urgent, so ancient, so torrenting -- nor known a book which continues to flow through my life long after I have notionally "finished" writing it. I feel deeply passionate about the ideas, rivers and people who run through its pages; among them Yuvan Aves, the young Indian writer, campaigner and naturalist with whom I am fortunate to have been friends for six years or so now, and whose home city of Chennai is at the core of the central section of this book. There is nothing so powerful as an idea that changes the world, and the ideas at the heart of the young Rights of Nature movement have the potential to do so. Since Ecuador recognised, in its Constitution in 2008, the inalienable and fundamental rights of Nature (Pachamama) to exist, to flourish and to persist, and charged the state with the guarantee of those rights, and with enforcing the repair of damage should those rights be violated, the world has seen the spread in number and consequence of Rights of Nature cases and thinking, across and up and down jurisdictions. If you find the idea of a river having rights initially confronting, remember that in European and American law, corporations have both rights and legal personhood (the right to bring suit in court). Why should a company founded two days ago have rights, but not a river that has flowed for tens of thousands of years? It's a form of socially normalised madness. Because these are all places in which rivers are being imagined otherwise. Rivers desperately need new stories told about them -- and some of those stories are very old, and have been forgotten. The dominant story now is one of river as resource, not river as life force. In India, in Canada / Nitassinan, in Ecuador, different forms of moral imagination are at work, or trying to be heard, so I travelled there to meet people and places where radical revisions are being attempted to the natural contract. It was an honour to write about the rivers, marshes, lagoons and creeks of Chennai, and to do so in the company of -- and seeing through the eyes of -- Yuvan Aves and his fellow campaigners, who are trying to imagine and implement a just future for Chennai's many water bodies, inspired by the Tamil word palluyir, meaning "all of life". Despair is a luxury and hope is a discipline. I watched Yuvan and his friends and colleagues struggling to drive change for the better, despite the threats and power levelled against them. In the face of such courage and moral clarity, what right would I have to sit back and say that I despair? As my indefatigable friend Rebecca Solnit puts it, "You are not giving up, and neither am I. The fact that we cannot save everything does not mean we cannot save anything, and everything we can save is worth saving." Hope is a discipline because it requires vigilance, concentration and lucidity to imagine other, better possible futures -- and then to push onwards in search of their realisation. And though there were times and stretches of the Cooum or the Kosasthalaiyar in which the river seemed as close to death as any I have ever known, there were moments of illumination and possibility, not least when accompanying the Turtle Patrol overnight, as it walked the beach to secure the safety of thousands of olive ridley sea turtle eggs each night during the nesting season. As sun broke on the night I had walked with the patrol, the first turtle hatchling of the season broke through the surface of the sand in the hatchery, and we carried her towards the surf and watched as ancient instinct drove that tiny, perfect creature to seek the water. Hope, right there!...