The textbook "Tool of the Historian" by Ahasver von Brandt offers a comprehensive introduction to the Historical Auxiliary Sciences. It is aimed at students and those interested in history and provides essential knowledge necessary for understanding and analyzing historical sources. Brandt, who worked as an archivist and professor, developed this work based on his teaching experience. It is considered an indispensable companion for introductory seminars on medieval history and has established itself as one of the best-selling books in this field. With clear explanations and practical examples, it is suitable for both beginners and advanced learners who wish to deepen their knowledge in historical studies.