Water management has become a major issue for public policies at any latitude. How and why this happened could not be assessed efficiently without developing a longitudinal and comparative analysis, such as the one in this book. Institutional arrangements for the provision and the use of water are peculiarly persistent as well as remarkably resilient: This makes them an ideal subject of an historical account. Not that history is worth writing about only when it treats immutable phenomena. On the contrary; its main purpose is to record changes and possibly explain them. But long-lasting continuity urges the scholar to venture into the remote past, since only there are to be discovered the initial causes and the deeper meanings of the institutions under scrutiny. Also, continuity makes the strength of path-dependency all the more evident and consequently underlines the weight of history.