Hermann Günther Graßmann was one of the 19th century most remarkable scientists, but many aspects of his life have remained in the dark. This book assembles essential, first-hand information on the Graßmann family. It sheds light on the family struggle for scientific knowledge, progress and education. It puts a face on the protagonists of an exciting development in the history of science. And it highlights the peculiar set of influences which led Hermann Graßmann to brilliant insights in mathematics, philology and physics. This book of sources is meant to complement the biography of Graßmann and the proceedings of the 2009 Graßmann Bicentennial Conference (Birkhäuser 2010). Roots and Traces will interest all scholars working on Hermann Graßmann and related topics. It offers newly discovered pictures of family members, historical texts documenting life in this exceptional family and an English translation of these previously unpublished papers. Text in German and English.