  It is important in the consideration of any of Dietrich of Freiberg’s writings to remember that he was the kind of philosopher who constructed his various works from a metaphysical point of view, whether they were scientific studies on light or theological treatises on the beatific vision. For care and attention to developing a correct account of the nature of being, he tells us, will allow the philosopher to avoid many errors. The concept of being (ens), he notes, is the most fundamental of notions, distinguishing a thing from nothingness. Indeed, one can find many places in his writings where an important philosophical point or crucial distinction hinges on what Dietrich understands to be the correct notion of being, or essence, or quiddity. It is best then to begin the development of an account of Dietrich as a philosopher by attending to his metaphysics.