Richard Sylvan and Val Plumwood were eminent twentieth-century Australian philosophers who, in the way of philosophers, devoted their lives to examining fundamental assumptions about thought and the world. Though they were both renowned logicians - and probed metaphysics, ethics, epistemology, social and political theory and economics - it was their determination to fuse the practical and the intellectual, to 'walk the talk', that made them special. The world they sought to elucidate was not primarily interior; not for them navel-gazing or abstract theorising, but a passionate concern about the non-human world and the non-human others with which we share it: Sylvan was convinced of the culpability of the philosopher who could 'fiddle while the Earth begins to burn'. They were renowned as practical and rhetorical defenders of Australia's forests, as zealous conservationists who not only campaigned for the non-human world but tried to codify philosophically an 'environmental culture' that would be ethically and rationally engaged with it. Their philosophical endeavours to provide a modern foundation for such a culture were as much rooted in the forests they inhabited and worked physically to protect as in the academy; indeed Plumwood claimed that her every word had 'the thought of the forest behind it, as the ultimate progenitor and meaning of my speech'. To them, the separation of physical and intellectual labour was as wrong as, and symptomatic of, human alienation from nature; and they strove to reconnect these artificial, dangerous dichotomies. While Sylvan strove for the general 'greening of ethics', Plumwood became increasingly aware of other toxic dichotomies that infused gender politics, going on to gain recognition as a pioneering eco-feminist. Sylvan and Plumwood were iconoclastic, even anarchic, and spoke what they believed without concern for social nicety. In their lives and in their works they promoted an 'eco-logic' to live by, a world view that, in the years since their deaths, has become ever more essential. In the present volume Dominic Hyde explores their intertwined lives and complex ideas with lucidity, respect and clear-sighted affection.