Skip to main content

Risner, Friedrich


(b. Herzfeld, Hesse, Germany; d. Herzfeld. ca, 1580)

mathematics, optics.

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

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Risner, Friedrich." Complete Dictionary of Scientific Biography. . 20 Jan. 2019 <>.

"Risner, Friedrich." Complete Dictionary of Scientific Biography. . (January 20, 2019).

"Risner, Friedrich." Complete Dictionary of Scientific Biography. . Retrieved January 20, 2019 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.