This book represents the culmination of an endeavor begun by the author, with the support of Richard Forman and Zev Naveh, more than a dozen years ago. It builds on the author's previous successful publication, Landscape Ecology, A Widening Foundation, by addressing a range of additional topics and discussing the new theoretical and methodological concepts that have emerged during the past decade of research. Particular attention is paid to the fact that interventions in the landscape can be made with the best intentions yet cause serious damage! Against this background, the author explains the need to study "landscape units" by applying methods comparable to those used in clinical diagnosis - hence ecologists can be viewed as the "physicians" of ecological systems.