This article attempts to determine the place of the late Humanist physician and natural scientist Anselmus Boetius de Boodt (1550-1632) in the context of Rudolfine knowledge. Above all, it analyses his encyclopaedic work 'Gemmarum et lapidum historia' (Hanau 1609), which he wrote during his stay at the Rudolfine court. De Boodt's systematic mineralogical classification is characteristic by its critical work with earlier authors, by the emphasis on empiricism and by logical assessment which stems from the Scholastic interpretation of Aristotle's concept of nature. In the context of early 17th-century pansophy and natural science, de Boodt tended towards an analytical and exact course. His empiricism, which rests on experimental and verifiable experience, his resistance to magic and his original cosmology based on deep religious convictions regarding the forming divine spirit are very different from two important expressions of Rudolfine natural science: Croll's medicine, based on the Paracelsian system of correspondences, and Kepler's Platonising cosmology. In spite of their proclaimed rationality, however, de Boodt's experiments were still influenced by period magical thought. The study further considers the more specialised theme of de Boodt's relationship to alchemy - his interpretation of the relationship between light and precious stones, his rejection of the Paracelsian doctrine of signatures, and his position to the various directions taken by contemporary alchemy. His position with regard to transmutational alchemy was pragmatic and theoretically not clear cut, oscillating between admitting the possibility of transforming silver into gold, to the rejection of the idea that metals could be reduced to their primal matter. According to the report of the French alchemist Nicolas Barnaud (1538 - pre-1607), de Boodt supposedly successfully experimented with the transformation of mercury into gold. At the same time, it is characteristic of de Boodt that he interprets nature and human experience and their principles on the basis of the principle of 'identity' rather than on that of 'analogy', which was the basis of alchemical thought. The lack of clarity in de Boodt's relationship to alchemy is also expressed in the symbolism of his personal device.
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