Who is Georges Duby from Travels in Hyper Reality: Essays and what is their importance?

Georges Duby did a study on the theory of the three orders in his book "The Three Orders: Feudal Society Imagined", which was written in 1980. Duby's book explores ancient biblical writings that describe the people being divided into three orders: the clergy, the soldiers, and the people. Eco respects Duby's work a great deal due to the conscientiousness and rigor he puts into it.