The Liber introductorius is the main work of Emperor Frederick II's astrologer, Michael Scot. Yet reconstructing the life and career of this 13th-century scientist and translator is notoriously difficult : much of the available information is legendary or anecdotal and the attribution of the Liber introductorius in its entirety cannot be accepted uncritically. A poem by Henry of Avranches appears to place Michael's death before 12361. Nonetheless, certain sections of the Liber introductorius contain material that suggests a considerably later date of composition - indeed, even after the death of its dedicatee, Frederick II. This paper examines a selection of 'meteorological' sources found in the Liber introductorius2, with a view to clarifying both its authorship and the circum
This article undertakes a detailed investigation of Razi's metaphysical theory of unity (wahda). In addition to providing the first overview of Razi's views on unity in a metaphysical context, the paper tackles a set of specific philosophical issues that marked the history of ancient Greek and medieval henology in both the Arabic and Latin traditions. Is unity internal or external to the essence ? In what sense is it accidental ? What is its relation to existence ? And how is it predicated of things ? In order to address these questions, I examine a wide range of texts by Razi, but focus in particular on his philosophical or hikma works, which consist of both independent treatises, such as the Mabahit and the Mulahhas, and of commentaries on works by Avicenna, the Sarh al-Isarat and the Sarh 'Uyun al-hikma. Although I prioritize Razi's discussions of unity in the context of the 'common notions' (umur 'amma) as these appear in the Mabahit and the Mulahha, my analysis also draws on other key works of Razi's corpus, such as the Matalib and the Tafsir. The analysis shows that Razi's theory of unity should be regarded as a critical and original development of Avicennism during the twelfth century and marks a pivotal chapter in the history of henology in Islam.
This article builds on the recent discovery of the Perspectiva cum sit una (PCSU), a previously unknown early 14(th)-century optical treatise, and presents several new findings on its reception in late medieval manuscript sources from Paris, Germany, and Italy. The first of these sources is a Franciscan sermon from Thuringia, whose exact quotations from the PCSU, attributing the text to Thomas Bradwardine, provide further evidence of Bradwardine's possible authorship. Second, the article identifies scattered borrowings from the PCSU in two sets of glosses to John Peckham's Perspectiva communis in the manuscripts Vat. lat. 3102 (probably Parisian) and Wien, ONB, Cod. 5447 (most likely Italian). Thirdly, it uncovers the crucial role the PCSU plays in Wigandus Durnheimer's Perspectiva, completed in Paris in 1390. This comprehensive compilation of medieval optical knowledge incorporates nearly forty excerpts from the PCSU. Along the way, the article offers new insights into the manuscript and textual interplays surrounding late medieval optics, such as the reception of Blasius of Parma's Questiones super Perspectiva communi within the glosses to Peckham, and the profound influence of Parisian authors - including Henry of Langenstein, Nicole Oresme, Themo Judaei, and Pierre d'Ailly - on Durnheimer's treatise. The article is complemented by a synopsis of the PCSU's propositions and structure, edited from the main manuscripts of the treatise.
This article investigates Averroes' conception of sexual differentiation at the intersection of logic, ontology, biology, and politics, focusing in particular on his conception of woman and her place within the definition of the human being. Aristotle never offered a definitive answer to the concrete question of how to define the human being and how to situate sexual difference within it. His corpus instead reveals a persistent tension between the universalist scope of his theory of essence and the contextual assessments that shape his anthropology and politics. Averroes inherits this unresolved framework and rearticulates it in original terms. By highlighting the largely overlooked legacy of Galen, particularly his theory of complexion, and by engaging with little-known texts across Averroes' corpus, this analysis reveals how he reshapes a theory of the human in which sexual difference neither collapses into ontological hierarchy nor dissolves into sociological contingency. What emerges is a conception of woman that functions as a critical hinge for rethinking the very categories of definition, essence, and accident in conceiving what it means to be human.
