In this episode of CSS Breakdown: Book by Book, Season 08, Episode 04, we explore Chapter 4 of 'International History and International Relations', focusing on the complex concept of sovereignty. This chapter highlights how knowledge of sovereignty is vital for understanding state behavior in International Relations and appreciating the driving force of European and international history. We delve into its historical origins and development, from its conceptualization in ancient Greece and Rome, where it was associated with the sovereignty of law, to the medieval period's debates on where authority resides—in the people or the ruler. The episode will then examine how Jean Bodin systematically articulated the theory of state sovereignty in 1576, establishing it as a permanent attribute of the state itself, and how the Peace of Westphalia in 1648 further consolidated the sovereign state as the singular mode of European constitutional authority, establishing the legal equality of states. We also discuss the social contract theories of Hobbes and Rousseau, which legitimized the state as a unit based on the will of the community. Looking at contemporary sovereignty, the episode will explore its internal and external aspects, positive and negative dimensions, and the ongoing tension between absolute and relative interpretations, especially in the context of international law versus international relations perspectives. We’ll consider the impact of colonialism, the rise of international organizations, and the European Union's influence on state sovereignty, revealing that this core concept remains ambiguous, challenged, and flux-ridden.