Spirn situates Ian McHarg’s influence within the institutional, pedagogical and intellectual formation of post-war environmental landscape architecture. Her iconic argument is that Design with Nature cannot be understood only as a technical overlay method; it emerged from a broader attempt to make landscape architecture an instrument of environmentalism. The theoretical contribution lies in analysing the tensions between science and design, preservation and management, region and locality, nature and culture. Methodologically, Spirn combines archival sources, professional reports, interviews and firsthand experience, reconstructing both achievements and unresolved contradictions. The conceptual operation is contextual genealogy: a celebrated method is returned to the networks of teaching, collaboration and controversy that produced it. The wider bridge reaches landscape history, ecological planning, environmental education and design research. McHarg’s legacy becomes neither heroic nor dismissible, but an institutional ecology whose successes, blind spots and afterlives continue to organise disciplinary practice.