Samuel P. Hays is one of the most distinguished scholars in the field of environmental history and the leading thinker of its first generation. The range and quality of the scholarship collected here reflect his work as a teacher, scholar, and activist writing in environmental history and provide a powerful exclamation point to a long and distinguished career.The depth of Hays's research is evident on every page of this collection. He was not one who published just to publish; he wrote what was important and spoke to the heart of continuing debates about the environment from 1959, with the publication of Conservation and the Gospel of Efficiency to the present day.As well as representing his best work from the past four decades, this collection includes four pieces published here for the first time. One of these, the opening essay, is Hay's autobiographical account of his encounters with many participants in environmental studies and those vigorously involved in contemporary environmental politics. Amid the entire series of environmental dramas that have engaged his attention, he has sought "to establish the case that a perspective of change and evolution over time, the focus of the historian, can be of immense value in informing the ongoing debates over environmental affairs." This arguement runs through this work.