The states of the twenty-first century will not be divided along lines of wealth and poverty, democracy and authoritarianism, but between states that have preserved their capacity to shape the consciousness of successive generations and states that have lost it silently and almost unnoticed. In the twentieth century, the school stood at the heart of modern state-building. In the twenty-first, that same institution has become a site of the state’s erosion. The school is no longer the child’s only source of learning, but it remains the last institution through which the state can shape how its children relate to public life, the nation, and a shared future. When that bond weakens, the consequences are not immediately visible in examination results. They emerge instead in declining trust, weakened belonging, a more fragile collective consciousness, and the state’s diminished ability to carry its project forward across generations. This book introduces the concept of “educational sovereignty” as a new framework for understanding the relationship between education and the stability of the modern state. It starts from a single question: what happens to the state when the school loses its capacity to shape the shared space in which its people live together? This is not a book about education reform. It is a book about what happens to states when the meaning of the school changes. When the history of this century is rewritten, it will not be wars or artificial intelligence that define it, but what happened to schools.