In our time, Ted Toadvine observes, the philosophical question of nature is almost entirely forgotten - obscured in part by a myopic focus on solving 'environmental problems' without asking how these problems are framed. But an 'environmental crisis', existing as it does in the human world of value and significance, is at heart a philosophical crisis. In this book, Toadvine demonstrates how Maurice Merleau-Ponty's phenomenology has a special power to address such a crisis - a philosophical power far better suited to the questions than other modern approaches, with their over-reliance on assumptions drawn from the natural sciences. The book examines key moments in the development of Merleau-Ponty's philosophy of nature while roughly following the historical sequence of his major works. Toadvine begins by setting out an ontology of nature proposed in Merleau-Ponty's first book, ''The Structure of Behavior''. He takes up the theme of the expressive role of reflection in Phenomenology of Perception, as it negotiates the area between nature's own 'self-unfolding' and human subjectivity. Merleau-Ponty's notion of 'intertwining' and his account of space provide a transition to Toadvine's study of the philosopher's later work - in which the concept of 'chiasm', the crossing or intertwining of sense and the sensible, forms the key to Merleau-Ponty's mature ontology - and ultimately to the relationship between humans and nature.