© Springer Nature Switzerland AG 2020

R. Shamey, R. G. KuehniPioneers of Color Sciencehttps://doi.org/10.1007/978-3-319-30811-1_15

15. von Freiberg, Dietrich 1245–1320

Renzo Shamey¹   and Rolf G. Kuehni¹  

(1)

Color Science and Imaging Laboratory, North Carolina State University, Wilson College of Textiles, Raleigh, NC, USA

 

 

Renzo Shamey (Corresponding author)

Email: rshamey@ncsu.edu

 

Rolf G. Kuehni

Email: rolf_kuehni@ncsu.edu

15.1 Study of the Rainbow

References

Sculptural image of Dietrich von Freiberg on the Fortuna fountain in Freiberg, Saxony, Germany by Bernd Göbel

It is generally assumed that Dietrich (Theodoric) was from and active in Freiberg in Saxony, Germany. However, it is known that he also spent a considerable amount of time elsewhere in Europe including France and Italy. Unfortunately, his life dates are not accurately known either, though he is believed to have been born ca. 1245.

After studying theology, he proceeded to study logic, in particular the writings by and about Aristotle. In 1271, he was a lecturer in the Dominican Monastery of Freiberg. He studied theology at the University of Paris, France, between 1272 and 1275. He was elected to be the leader of the Dominican Order in the German region in 1293. Around 1297, he was elected to the position of master of theology in Paris. In later life, he continued to be a leader in the German Dominican Order but also spent time in Toulouse, France, and in Piacenza, Italy. An influential German Dominican of his time was Meister Eckhardt (ca. 1260–1327). Both made important contributions to philosophy and theology of the time. Dietrich is also considered to be an early advocate of the scientific method. He is believed to have died ca. 1320 [1].

15.1 Study of the Rainbow

Dietrich had an interest in natural sciences and wrote a number of papers on various matters often covering a given subject and its philosophical implications. On the matter of color and light, he wrote three papers:

De iride et radialibus impressionibus (On the rainbow and impressions created by radiation)

De coloribus (On colors)

De luce et eius origine (On light and its origin)

There is disagreement on the sequence of these writings. It is generally assumed that they were written between approximately 1305 and 1312 [2].

In De iride, Dietrich offered an independent experimentally supported, essentially correct, hypothesis of the origin of the rainbow. This involved filling a round glass bottle with water and observing under what angles of view a beam of sunlight was reflected and refracted by glass and water. As was mentioned in Part II, a similar approach was used independently by the Persian philosopher/scientist Kamal al-Din Farisi (1267–1319) which he described in Tanqih al-Manazir [3]. Dietrich compared his results to the observations of a beam of sunlight passing through a hexagonal natural crystal that was called “iris” (Fig. 15.1) (Glass prisms only began to be used in the fifteenth century) as well as in crystal spheres and water droplets. He used extensive experiments to arrive at an interpretation of the primary and secondary rainbows (Fig. 15.2).

Fig. 15.1

Drawing of the passage of beam of sunlight and its refractions through a hexagonal natural crystal, the beam entering from the bottom left

Fig. 15.2

Two pages of the handwritten manuscript of De iride, with an illustration of the formation of the rainbow at a specific angle in water droplets of rain [2]

In De coloribus, Dietrich discussed the views of Aristotle, Avicenna, and Averroes. In regard to primary colors, he did not differ from Aristotle’s idea that chromatic colors are the result of mixtures of the extremes, white and black. However, his investigations of the rainbow made him change the sequence of the chromatic colors from Aristotle’s to be in agreement with the sequence he observed in his hexagonal device and in the rainbow. He said:

The second kind [chromatic colors] differ thus in that in red and in yellow whiteness prevails, while blackness predominates in green as well as in blue … in the first combinations whiteness predominates, but red is nearer to the extreme, which is white, and yellow farther away. In combinations where blackness dominates blue is closer to black and green is less so. The middle colors stretch in this order to form the rainbow.

Thus, his sequence of primary colors is white–red–yellow–green–blue–black. He did not include purple because it does not appear in the rainbow. This sequence of the chromatic primaries has a factual basis, while those of later authors, such as Leon Battista Alberti (1404–1472) [4] continued to be based on philosophical ideas of the time.

The next chapter includes a discussion of advancements in the field during the Scientific Revolution Period.

References

1. 1.
   K. Flasch, Dietrich von Freiberg: Philosophie, Theologie, Naturforschung um 1300 (Klostermann, Frankfurt/M., 2007)
2. 2.
   Dietrich, in Natural Science Writings of Theodoric: In Vol. 4 of Theodoric, Opera Omnia, ed. by M.R. Pagnoni-Sturlese, R. Rehn, L. Sturlese, W.A. Wallace. Corpus Philosophorum Teutonicorum Medii Aevi, vol. 4 (Felix Meiner Verlag, Hamburg, 1985)
3. 3.
   K. al-Farisi, Tanqih al-Manazir (Deccan, Hyderabad, 1928). Two volumes
4. 4.
   L.B. Alberti, On painting (Cambridge University Press, Cambridge, 2011)