c. 1250-c. 1310

German natural philosopher who studied at the University of Paris, gaining a Master of Theology. His major work, De iride et radialibus impressionibus (On the rainbow and radiant impressions), written around 1305, was unusual in its use of experimentation to replicate a natural phenomena. Dietrich established the source of rainbows as light interacting with raindrops, and his work was not surpassed until the time of Descartes and Newton. He also wrote works on theology, philosophy, optics, and astronomy.