This article presents the results of a comparison of didactics textbooks in two countries: on the one hand it examines a textbook in the tradition of German Didaktik, and, on the other hand, a textbook in the tradition of "Instructional Design" from the USA. The main research question is: How do authors write didactics textbooks? Is it possible to gain an understanding from different textbooks about the self-understanding of the academic field of "didactics"? In answering these questions, the aim is to draw some conclusions in relation to the structures of the disciplines in these different traditions within the field of educational studies. The results show that authors of textbooks work eclectically. Didactics is also an eclectic discipline. "Eclectic" in this context means that there are two main tasks in the didactical field, selection and integration, and both can only be performed in an inter-disciplinary, historically evolved, culturally specific, argumentative and systematic way. (Contains 3 notes, 2 tables, and 11 figures.)