This textbook examines interaction, reciprocity, dualism, conflict, and personality in the work of Georg Simmel. These themes, which made Simmel the founder of relational sociology, are presented uniquely in the light of intimate relations. According to Simmel, intimate relations rather than the individual constitute the fundamental stratum of human culture. By relating objective social facts to subjective experience, Simmel also opened up a new way of understanding human life in the early 20th century. Using Simmel’s theory of reciprocity, this book follows an innovative method of interpretation, providing a quantitative perspective of lived experience. This book analyzes Simmel’s ideas from the viewpoint of modern hermeneutical philosophy and sociology. Fellmann expertly presents the historical context of Simmel’s concepts, and their influence on other sociologists and philosophers, especially in Germany. Written in an engaging style, this book is suitable as a core text in undergraduate and graduate courses on sociological theory and continental philosophy. Additionally, given the new focus on Simmel and intimate relations, the book is of interest to scholars of relational sociology, history of sociology, continental philosophy, history of philosophy, philosophy of culture, and philosophical anthropology.