The textbook is an essential individual studying and learning tool which helps the student gain insight into the theoretical system as well as the practical issues of a particular field of study. It can also raise interest in and develop a commitment to a discipline with the aid of appropriate tasks and exercises. However, most importantly, the textbook offers a learning strategy for the study of a particular discipline, which facilitates the acquisition of learning and studying strategies for life. This article presents content-selection principles that can be derived from the nature of scientific learning, from the organisation and operation of the personality and from the psychic nature of learning. These principles, which are introduced through examples of teaching and learning communication, can form the basis for the effective selection of textbook theory and textbook practice.