The Second Vatican Council (1962-1965) - which finished its work just thirty years ago - has rightly been described as one of the most important events in the history of the Church since the Reformation and the Age of Enlightenment. It is in particular the Pastoral Constitution Gaudium et spes «On the Church in the Modern World» which marks a milestone on the Church's way into modernity. It forms a bridge designed to overcome misunderstandings of the past, points of conflict and rifts between the Church and modern society. It purports to guide the differing positions towards a constructive dialog. The central criterion and the crucial question of this new definition of the relationship in all areas, such as culture, politics, science and economics is the criterion of «Relative Autonomy» - the topic treated in this book.