A Journey into the (Un)known. Borderlands of Knowledge for Leonhard Rauwolf (1535Rauwolf ( ?-1596 The Augsburg physician Leonhard Rauwolf is known to the history of Western sciences for "discovering" the exotic flora of the Near East. This article deals with the social background of his studies in Germany and France and his perception of foreign lands, plants, and peoples. Before Rauwolf started his journey at Marseille in 1573 he had received a proper education in practical botany at Montpellier under Guillaume Rondelet. He had also collected about 600 specimens of plants in his herbarium. According to the common medical conventions of his time -most prominently represented by the Renaissance anatomist Andreas Vesalius -in his travel account Rauwolf claimed to tell only what he had seen, experienced, observed by himself, or touched with his own hands. Contrary to his own claim of pure "autopsy", or direct experience, however, Rauwolf's Aigentliche Beschreibung [Actual Description] was composed from different sources. As previously unnoted manuscript letters from the Trew-collection at the University Library of Erlangen show, editorial work on Rauwolf's book was a lengthy process. The final composition ended up drawing on such different sources as the Old and New Testament, ancient natural philosophy, Christian travel literature and sermons, more recent botanical books, oral information from other academics, fellow travellers or indigenous people, and -finally -Rauwolf's own impressions and observations. Keywords: Leonhard Rauwolf, sciences and medicine of the 16 th century, botany, empiricism, travel literature Schlüsselwörter: Leonhard Rauwolf, Naturwissenschaft und Medizin im 16. Jahrhundert, Botanik, Empirismus, Reiseberichte Grenzen werden, anders als natürliche Barrieren, durch politische und kulturelle Bedingungen bestimmt. 1 Geographische oder klimatische Besonderheiten und große Gewässer mögen die Migration von Tier und Mensch behindern oder unmöglich machen. Die Begegnung mit dem Unbekannten mag bei einem Reisenden Gefühle der Fremdheit auslösen. Wesentlich für das Bewusstsein, sich einer Grenze genähert oder sie überschritten zu haben, dürften aber Erfahrungen soziokultureller Art sein: das Wissen, sich nun jenseits der vertrauten sprachlichen, kulturellen und politischen Welt zu bewegen. Expeditionen in ein von Menschen gänzlich unbewohntes Land stellen so eine Sonder-oder Extremform dieses "Kulturschocks" dar: In der