THEODORIC (DIETRICH) OF FREIBERG

German Dominican philosopher, theologian, and precursor of modern science, otherwise known as Theodoricus Teutonicus de Vriberg and Thierry de Fribourg;b. Freiberg in Saxony?, c. 1250; d. 1310 or shortly thereafter. An eclectic and independent thinker, Theodoric may be characterized as Neoplatonic and Augustinian in theology and as Aristotelian in philosophy; he was also an indefatigable researcher whose experimental and theoretical work on the rainbow was several centuries in advance of his time.

Life and Works. Theodoric was present at the University of Paris when henry of ghent disputed his first quodlibet in 1276. He was elected provincial of Germany by the general and provincial chapter of Strassburg in 1293, an office he held for three years. It is probable that he became a master in Paris in 1297. He is identified as "Master Theodoric, Prior of Würzburg," in a document describing the work of a commission in which he took part at Koblenz in 1303. He was present at the general chapter of the order held in Toulouse in 1304, at which time the master general, Aymeric, asked him to put the result of his investigations on the rainbow into writing. The general chapter held at Piacenza in 1310 appointed him vicar provincial of Germany. In one of his last works he wrote that he had given up teaching for preaching, and he is noted as the first scholastic to preach in German (H. Denifle and F. Ehrle, Archiv für Literaturund Kirchengeschichte des Mittelalters, 7 v. 2:421). He exerted considerable influence on the German mystics, particularly Berthold of Moosburg, Meister eckhart, and Johannes tauler.

Theodoric's writings were mainly in the form of opuscula on a variety of subjects in logic, psychology, metaphysics, theology, and natural science. In logic he dealt with the predicaments, the notion of quiddity, the nature of contraries, and the notions of more and less. His psychological treatises were concerned with the intellect and its object and with habits, while his metaphysical works dealt with essence and existence, accidents, and the heavenly bodies and their movers. In theology he was concerned with such subjects as the beatific vision, the knowledge of separated substances, the attributes of glorified bodies, and the Body of Christ after His death. His works in science include treatises on light, color, the rainbow, elements, compounds, and time.

E. Krebs has edited Theodoric's psychological writings; A. Maurer, his work on quiddity; F. Stegmüller, his works on time [Archives d'histoire doctrinale et littéraire du moyen-âge 13 (1940–42): 155–221] and on the predicaments [ibid. 24 (1957): 115–201]; and J. Würschmidt [Beiträge zur Geschichte der Philosophie und Theologie des Mittelalters 12.5–6 (1914): 33–204] and W. A. Wallace (Methodology, 305–376), most of his scientific treatises.

Teaching. Theodoric's work on the predicaments draws heavily from Aristotle's Metaphysics and Averroës's commentary on the same and is particularly concerned with the modes of causal origin by which the categories are constituted, for example, the intellect's causality in the formation of universals. His theory of knowledge, as expounded in the work on the intellect, is markedly influenced by the liber de causis and by St. Augustine. Theodoric teaches that the agent intellect is unique in each man, that it is always in act, that it is what makes man be in God's image, and that it is a beatifying principle in the elect who see God in His essence.

Theodoric opposes St. thomas aquinas in denying the real distinction between essence and existence. Like the treatise on quiddity, that on essence and existence seems partially inspired by St. Thomas's De ente et essentia. Another metaphysical doctrine on which Theodoric sets himself in opposition to Thomas is his teaching on accidents, and particularly on whether it is possible for these to exist without a subject—which the German Dominican holds is absolutely impossible, both naturally and supernaturally. His view of the universe is Neoplatonic: it embraces God's unity, spiritual natures, souls, and bodies; interprets creation as a type of emanation; and conceives temporal development as a return to divine unity. Contrary to some authors, he was never a proponent of the metaphysics of light.

Theodoric's work in optics culminated in the first correct explanation of the primary and secondary rainbows in terms of the paths of light rays being reflected and refracted through spherical raindrops. His scientific methodology is a paradigm for the application of Aristotelian logic and dialectics to specific problems; it also anticipated the experimental methods of modern science. As a byproduct of this work, Theodoric elaborated a theory of light and color that attempts to explain such phenomena as the production of spectra and that links these to the structure of matter. He also worked out a theory of elements and compounds that accounts for the relations of the elements to primary matter. His analysis of gravitational motion allows for the fact that there might be a plurality of centers in the universe toward which matter gravitates. He also eliminated the generator as an efficient cause of falling motion, thereby anticipating later medieval developments in mechanics. His theory of the rainbow indirectly influenced the development of geometrical optics by Descartes and Newton.

See Also: science (in the middle ages).

Bibliography: e. krebs, "Meister Dietrich: Sein Leben, seine Werke, seine Wissenschaft," Beiträge zur Geschichte der Philosophie und Theologie des Mittelalters 5.5–6; (1905–06); "Le Traité De esse et essentia de Thierry de Fribourg," Revue néoscolastique de philosophie 18 (1911): 516–536. a. maurer, "The De quidditatibus entium of Dietrich of Freiberg and Its Criticisms of Thomistic Metaphysics," Mediaeval Studies 18 (1956): 173–203. w. a. wallace, The Scientific Methodology of Theodoric of Freiberg (Studia Friburgensia, new series 26; Fribourg 1959); "Gravitational Motion according to Theodoric of Freiberg," Thomist 24 (1961): 327–352; "Theodoric of Freiberg on the Structure of Matter," Proceedings of the Tenth International Congress of History of Science, Ithaca, N.Y. 1962, 2 v. (Paris 1964) 1:591–597. É. h. gilson, History of Christian Philosophy in the Middle Ages (New York 1955) 433–437, 753–755.

[w. a. wallace]