Manuscript and Textual Echoes of the _Perspectiva cum sit una_: New Evidence of Its Authorship and Reception in the Fourteenth and Fifteenth Centuries

This article builds on the recent discovery of the Perspectiva cum sit una (PCSU), a previously unknown early 14th-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, ÖNB, 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.