This volume with its fourteen scientific contributions takes part in the discussion on the importance of history, its preservation, and investigation and provides examples of scientific analysis of historical sources of various kinds. It begins with reflections by Andrzej Radziminski on delicate processes of historical transmission. They can be disturbed by various factors, "unfortunately, many facts will never go down in history, while others, deliberately changed or forgotten, will create a completely distorted picture." Through new facts and/or novel analysis of the sources, the investigation of history remains eternal. The idea is reflected in the other contributions, in which recognized Polish and German scientists take up new topics or research them anew.