This book argues that value persists in each individual living thing and that value in such things as ecosystems supervenes on the primary value of individuals. The book presents a new biocentric ethic based on Aristotle's metaphysics. It traces key ideas through Western Philosophy from Aristotle to modern theories of environmental ethics and demonstrates that Aristotelian notions have a significant role to play in understanding human moral obligations to nature. It is a scholarly book written in an easy style that will make it accessible to undergraduate students and those interested in Green philosophy.