MacKaye’s romance with primeval wilderness and moralizing about what he called "metropolitan invasion" are less pertinent than his recognition of the landscape of development as another nature—an "industrial wilderness." Even more significant was the way in which he theorized about this "wilderness of civilization" as a geological formation read not for its shape but for its recordings of change and movement. Like undiscovered territory, this landscape awaited The New Exploration, as MacKaye’s most popular book is titled.