A Philosophical Path for Paracelsian Medicine: The Ideas, Intellectual Context, and Influence of Petrus Severinus: 1540-1602 (review)

Tracing the reception of Paracelsus's often enigmatic ideas has led historians to pay attention to the ways in which editors first fashioned his texts for publication and to the efforts of individual followers to make his theories fit specific intellectual milieux. Jole Shackelford's sweeping and penetrating study of the design and reception of Petrus Severinus's Idea medicinae philosophicae (1571) convincingly establishes Severinus as one of the most important figures among those articulating Paracelsian traditions. On the one hand, Severinus linkedParacelsian medical theory to ancient authorities, especially to the authentic (i.e., uncorrupted) precepts of Hippocrates. On the other, he gave shape to a more systematic expression of Paracelsian thinking by placing it within the context of Platonist metaphysics. According to Shackelford, the combination brought the Idea medicinae within the genre of a sort of literature that sought a compromise between university medicine and Paracelsianism as well as between humoral pathology and chemical cures.

Especially it was Severinus's notion of seeds, or semina, that caught the attention of later commentators. Semina were seed-like "reasons" (rationes seminales or logoi spermatikoi) that were altogether imperceptible to the senses but that, nevertheless possessed the preordained plan for each physical thing. As such, they existed as the intermediaries between divine ideas and material bodies, sharing both spiritual and corporeal characteristics, possessing the principle of vitality, and accounting for both healthy and morbid physical change. Causative semina worked together with another part of Severinus's philosophical medicine, namely "tinctures." These he described as pure forms or species that could be transfered from one thing to another causing changes in the semina of an affected body. Such tinctures within semina possessed the mechanical knowledge (scientia mechanica) of the chemical processes by means of which changes in a body took place. Thus, curing disease could take place by means of "transplantation" (in which the vital tinctures in chemically prepared compounds altered morbid tinctures) or by altogether removing offending semina and tinctures and strengthening, again by means of the vital spirits in chemical compounds, the body's vital balsam.

Shackelford's discussion makes sometimes-difficult concepts both coherent and accessible, and pierces well into the intellectual details of Severinus's Idea. This alone would make the study a valuable contribution to the history of natural philosophy and medicine in the sixteenth and seventeenth centuries. However the treatment of Severinus extends even further and establishes the relationships that contributed to a supportive environment for Paracelsian ideas in Denmark, and comprehensively surveys the reception and application of Severinus's thinking thereafter. In particular, Shackelford explores the informal interaction between Severinus, who was appointed royal physician in 1571, Johannes Pratensis (1543–76), who became professor of medicine at the University of Copenhagen, and Tycho Brahe, who explored what he called "terrestrial astronomy" (68–69: i.e., the chemical arts) at his island home of Hven. The combination of courtly and academic encouragement for Paracelsian ideas made the early 1570s a heydayfor Paracelsian medicine and chemical philosophy in Denmark, even thoughParacelsianism itself never became part of the official university curriculum, a consequence, in part, of the early death of Pratensis in 1576.

While a formal didactic presence for Paracelsian ideas failed to become reality, Shackelford shows that Severinus's own interpretation of the metaphysical and physical underpinnings of medicine proved to be, in its own right, an excellent vehicle for disseminating Paracelsian theory. A richly fleshed out survey of authors in France, England, Central Europe, and Scandinavia who either promoted or quarreled with Severinus's Idea demonstrates the text's ongoing influence. In this regard, two authors, each of whom wrote commentaries on the Idea, earn special attention. The first, Ambrosius Rhodius, further explicated the nature of the elements (a point of fundamental disagreement between Aristotelian and chemical philosophers) and expanded...