The book is founded upon this new definition: sustainability is the possibility that humans and other life will flourish on Earth forever. There are obstacles to this hopeful vision, however, and overcoming them will require us to transform our behavior, both individually and collectively. Ehrenfeld identifies problematic cultural attributes—such as the unending consumption that characterizes modern life—and outlines practical steps toward developing sustainability as a mindset. By focusing on the “being” mode of human existence rather than on the unsustainable “having” mode we cling to now, he asserts, a sustainable world is within our reach.