This chapter articulates the foundational propositions of Hsu’s theoretical framework for studying literate civilizations, focusing on the ontological and epistemological relationship among psychology, behavior, and culture. It introduces two central conceptual tools—role and affect—to explain how human behavior is shaped not only by rational decisions or social norms, but also by culturally patterned emotional forces. Building on this basis, Hsu formulates the Affective Man Hypothesis to challenge the limitations of the Economic Man and Social Man models, arguing that affective needs, such as status, security, and sociability, are the primary drivers of behavior in all human societies. The chapter also refines the typology of human needs by distinguishing between role-based and affect-based motivations. In its final section, the chapter explores the reciprocal relationship between culture and personality, proposing that cultural norms shape individual psychology, while the collective behavior of individuals in turn sustains and modifies cultural systems. Hsu highlights the relative stability of affective patterns in contrast to the faster-changing roles, offering an analytical perspective on how cultural transmission and transformation unfold over time.