Witelo - also known as Erazmus Ciolek Witelo, Witelon, Vitellio, Vitello, Vitello Thuringopolonis, Erazm Ciołek, (born ca. 1230 probably in the village of Borek in Lower Silesia; died after 1280, before 1314), was a Silesian and Polish friar, theologian and scientist: physicist, natural philosopher, mathematician, precursor of perception psychology.
Witelo's mother was from a Polish knightly house, while his father was a German settler from Thuringia. He called himself, in Latin, "Turingorum et Polonorum filius"—"a son of Poland and Thuringia." He studied at Padua University around 1260, then went on to Viterbo. He became friends with William of Moerbeke, the translator of Aristotle. Witelo's major surviving work on optics, Perspectiva, completed in approximately 1270-1278, was dedicated to William.
In Perspectiva, Witelo refers to other works that he had written. Most of these do not survive, but De Natura Daemonum and De Primaria Causa Paenitentiae have been recovered.
Perspectiva was largely based on the work of the Arab scholar Alhacen and in turn powerfully influenced later scientists, in particular Johannes Kepler. It also contains much material in psychology, outlining views that are close to modern notions on the association of ideas and on the subconscious.
Perspectiva also includes Platonic metaphysical discussions. Witelo argues that there are intellectual and corporeal bodies, connected by causality (corresponding to the Idealist doctrine of the universal and the actual), emanating from God in the form of Divine Light. Light itself is, for Witelo, the first of all sensible entities, and his views on light are similar to those held by Roger Bacon.
- Clemens Baeumker, "Witelo: Ein Philosoph und Naturforscher des dreizehnten Jahrhunderts," Beiträge zur Geschichte der Philosophie des Mittelalters, part 3, no. 2, Münster, Aschendorff, 1908.
- Władysław Tatarkiewicz, Historia filozofii (History of Philosophy), 3 vols., Warsaw, Państwowe Wydawnictwo Naukowe, 1978.