This fourth chapter, consisting of excerpts from Georg Simmel's Problems of the Philosophy of History, illuminates the organic links between “understanding” sociology and methodological individualism. In this epistemological essay, Simmel develops a neo-Kantian theory of knowledge that challenges the idea that objectivity implies independence from the knowing mind. He argues that all phenomena of historical interest are the products of mental processes, and that the historian must abstractly account for the meaningful development of mental contents that underlie particular historical actions, apprehended in their historical logic, not in the manner of a psychologist, but through a capacity for understanding that he shares with the historical actor. From this perspective, the historian, or more generally, the social scientist, must highlight the relevant elements of the actors’ situations, including knowledge forms or structures, and introduce interpretive assumptions that supplement facts, with the aim of clarifying the subjective unity of meaning that drives the social action.