Text in German. This volume contains a complete re-edition and study of the 'Fundamentals of the Course of the Stars'. This handbook on Religious Astronomy was hitherto known under the modern designation 'Book of Nut'. Since the standard edition in Egyptian Astronomical Texts I (eds. Neugebauer/Parker), five new sources could be identified, some of them containing considerably more text than those previously available. Four of them are papyri from the temple library of Tebtunis, which are published here for the first time. It becomes clear that the Dramatic Text in the Osireion of Abydos as a whole forms part of the 'Fundamentals'. The new sources also contain interesting textual variants of passages already known. Apart from the edition and translation, the study contains an exhaustive commentary focussing especially on the hitherto neglected religious aspects of the composition. Separate chapters deal with the relation between monumental and papyrus copies, dating and redactional history, inner-Egyptian practice of translating and commenting texts, the genre of Dramatic Texts and the books cited in the ancient commentary. A method of historical-linguistic text dating is developed. In an appendix, another mythological papyrus is edited which enriches the small corpus of so-called Dramatic Texts.