Architect Caspar Schmitz-Morkramer admits that he needs to rethink his stance in light of the escalating climate crisis - or at least really develop it! Just like the vast majority of architects. But he has his doubts. On the one hand, everyone says the same thing; on the other, there are contradictions at every turn. Before Caspar Schmitz-Morkramer can find his stance, he has to go through the labyrinth following a guiding thread. Der Nachhalt is the title of a series of publications that doc- uments and underpins the transformation of the architecture office of caspar. into a spe- cialist in sustainable construction. The Prologue is dedicated to the prerequisites for this task. This volume presents numerous facts and positions relating to sustainability in an in- formative, graphic manner, with just the right sense of irony and provocation