What is the purpose of a foundation? To what extent is the purpose relevant within the legal framework of a foundation based on German public law (paragraphs 80ff BGB)? As recent studies of German foundation law clearly indicate, there cannot be any doubt about the significance of the purpose, which up until now has often been described metaphorically as the soul or the heart of a foundation. Although these metaphors sound convincing in a general sense, they leave a lot of unanswered questions. This study sets out to find a more practically relevant understanding of the purpose of a foundation. The basic assumption of Philip Dylla's doctoral thesis is that the purpose of a foundation has a directive function, comparable to the instructions from shareholders' meetings of German limited companies (Gm BH). In consequence, the organs of a foundation are obligated to fulfill this directive in the best possible way. The directive function of the purpose of a foundation is derived from the constitutional right to set up a foundation, the laws governing legal entities and the specific fact that foundations are memberless. Starting from the basic significance of the directive function of the purpose of a foundation, Philip Dylla examines, among other aspects, the systematic interplay between the purpose and other parts of the foundation's statutes, as well as the possibilities of changing the purpose and the legal relationship between a foundation and its beneficiaries.