English summary: Among the numerous coevals of the 15th century who were eager to improve the condition of the church and the world, Nicholas of Cusa (1401-1464) is certainly one of the most interesting ones. He dedicated most of his lifetime to reforming, the marks of his activites being considerable: the Concile of Basle, his legation in Germany, his years as a bishop of Brixen, the foundation of a hospital in Kues, and his reform proposals as a cardinal in the Papal States. The broad horizon of the theologist, philosopher and canonist allows - beyond the reconstruction of single episodes - a comprehensive historical and theoretical approach to the problem of reform. This book binds together contributions of medieval historians and historians of philosophy. On the one hand it aims to expose the reform ideas and narratives standing behind Cusanus' activities, including their contradictions, and on the other hand to further put these narratives in the context of their theological and philosophical implications, as they appear in his theoretical writings. German description: Unter den nicht wenigen Zeitgenossen des 15. Jahrhunderts, die sich der Verbesserung des Zustands von Kirche und Welt verschrieben hatten, ragt Nikolaus von Kues (1401-1464) als einer der interessantesten heraus. Der weite Horizont des Kanonisten, Theologen, Philosophen, Bischofs und Kardinals erlaubt einen umfassenden historischen und theoretischen Zugriff auf seine vielfaltigen Reformbemuhungen. Cusanus ist daher ein idealer Fuhrer, um Historiker und Philosophiehistoriker miteinander ins Gesprach zu bringen. Der Band vereinigt Beitrage aus beiden Disziplinen, mit dem Ziel, die hinter den Aktivitaten des Cusanus stehenden Reformideen und Reformnarrative mitsamt ihren Widerspruchen freizulegen und zu seinen theoretischen Schriften ins Verhaltnis zu setzen.