Theodoric of Freiberg

[2] Theodoric became a Dominican friar very early on in his life, and he studied and taught at the local convent in Freiberg around the year 1271 (Teske 2003).

In medieval documents he is assigned the title of “magister”, which tells us he had a great deal of university training at an advanced level (Fuhrer 1992).

Fuhrer goes on to say that Henry of Ghent was known as “doctor solemnis” by his students, but ultimately states that there can be no certainty that they actually met or knew each other.

Exactly how long he remained in Paris in not clear, but it is agreed that he was made the prior of the Dominican convent in Würzburg around 1293 (Fuhrer 1992).

Theodoric was then “promoted” to the Provincial Superior for the province of Germany, the position previously held by Albert the Great (Pasnau 2010, Fuhrer 1992).

[4][5] Drawing from his two earlier works on light and colour, he wrote De iride et radialibus impressionibus (On the Rainbow and the impressions created by irradiance, c. 1304-1311), relying on geometry, experiment, falsification and other methods.

Currently on loan to universities in Providence, Rhode Island, the instrumentation does, indeed, simulate a droplet of water by which sunlight is reflected and refracted, thereby creating a rainbow.

One of Theodoric's contemporaries, Kamal al-Din al-Farisi, offered the same experimentally-established explanation of the rainbow (without any contacts between them) in his Kitab tanqih al-manazir (The Revision of the Optics).