One of the pioneers of Gestalt psychology, Wolfgang Koehler (1887-1967) broke new ground in numerous areas of human thought. This collection of writings spans Koehler's brilliant and productive career, beginning with his earliest formulations of Gestalt theory through to his last scientific paper--a perceptive overview of the significant advances of Gestalt psychology. Many of these essays have never before been published in English. Together they illustrate the diversified, highly innovative contributions of this great psychologist. But they go beyond that to clarify problems in psychology, philosophy, natural science, biology, and anthropology through the Gestalt approach.