(b. Herzfeld, Hesse, Germany; d. Herzfeld. ca, 1580)
Risner spent most of his scholarly life as the protégé and colleague of Peter Ramus, the renowned anti-Aristotelian humanist and educational reformer, who was accustomed to collaborating with younger scholars on mathematical subjects. Risner’s mathematical ability is evident from Ramus’ reference to his “assistant in mathematical studies, … Friedrich Risner, so well versed in mathematics” (Hooykaas, Humanisme, p. 45). In his will Ramus established a chair in mathematics at the Collège Royal de France and specified that Risner should be its first occupant. When legal disputes over the chair were settled in 1576, Risner accepted the salary but never lectured; he resigned a few months later and returned to his native Hesse, where he died after a long illness.
The most noteworthy result of the collaboration between Ramus and Risner was the immensely influential edition (1572) of the optical works of Ibn al-Haytham and Witelo. Risner produced the editio princeps of Ibn al-Haytham’s Optics (De aspcctibus) from two manuscripts discovered by Ramus, adding citations and subdividing the book into propositions. Witelo’s Perspectiva had already been published twice; but Risner improved the text by comparing several manuscripts, redrafted the figures, and added citations to corresponding propositions in Ibn-al Haytham’s Optics.
The collaboration of Ramus and Risner also resulted in the posthumous publication of Risner’s Opticae libri quatuor, which later influenced Snell. It seems that the book was begun during the early years of Ramus and Risner’s association; and it is probable that the basic outline was Ramus’, while Risner was given the task of providing appropriate demonstrations and discussion. Only the first of the four books is complete, however, and the final two consist of little more than the enunciations of the propositions. The work depends primarily on Witelo, although other ancient and medieval authors are also cited.
I. Original Works. Risner edited Opticae thesaurus Alhazeni Arabis libri septem, nunc primum editi. Eiusdem liber de crepusculis et nubium ascensionibus. Item Vitellonis thuringopoloni libri X. Omnes instaurati, figuris illustrati et aucti, adiectis etiam in Alhazenum commentariis, a Federico Risnero (Basel, 1572). Risner’s own Optica has been published as Opticae libri quatuor ex voto Petri Rami novissimo per Fridericum Risnerum ejusdem in mathematicis adjutorem, olim conscripti (kassel, 1606); and Risneri optica cum annotationibus Willebrordi Snellii, J. A. Vollgraff, ed. (Ghent, 1918).
II. Secondary Literature. On Risner’s life and works, see Bernardino Baldi, “Vite di matematici Arabi,” in Bullettino di bibliografia e di storia delle scienze matematiche e fisiche, V (1872), 461–462; R. Hooykaas, Humanisme, science et réforme: Pierre de la Ramée (Leiden, 1958); J. J, Verdonk, Petrus Ramus en de wiskunde (Assen, 1966 ), 66–73; and Charles Waddington, Ramus (Pierre de la Ramée), sa vie, ses écrits et ses opinions (Paris, 1855).
David C. Lindberg