Vision and cognition in the natural philosophy of Albert the Great (Albertus Magnus).

Albert the Great (Albertus Magnus, ca. 1197-1280) descended from a nobleman's family in Upper Suebia and studied natural philosophy and theology at the University of Padova, where he joined the Dominican order. Confronted with Aristotelian thought mainly in its Arabic modification (Avicenna, Al-Farabi, Averroes, Alhazen, Costa ben Luca and others) from his days in Padova, he elaborated in several books on the principles of natural philosophy, biology, brain and sense functions and psychology in addition to his theological and exegetic works. His observations and concepts on vision are discussed in detail. It is pointed out that Albert discovered some phenomena of vision not before known such as vestibular nystagmus and rod monochromacy, i.e. total colour blindness accompanied by photophobia. Based on clinical observations Albert also postulated a decussation of the optic nerve fibres at the optic chiasm. Albert's concept of higher order cognitive function is discussed and some of his explanations of dreams and neuropsychiatric disease on the basis of his cognitive model are mentioned. Albert's thoughts on vision and other sense perceptions, higher brain functions and cognition are considered as progressive elaborations of Galenic concepts as adapted by some Patristic theologians and the Arabic natural scientists and philosophers of the 9th-11th century.