ABSTRACT
In understanding the meaning of sustainability, it is useful to resort to basics. The term "sustain" comes originally from the Latin sustinere and into English through the Old French soustenir. Several historical cases illustrate the relationship of resources to problem solving, complexity, and sustainability. These are the collapse of the Western Roman Empire in the fifth century ad and the collapse of the Byzantine Empire in the seventh century ad, followed by Byzantine recovery. The economics of an empire such as the Romans assembled are seductive but illusory. The returns to any campaign of conquest are highest initially, when the accumulated surpluses of the conquered peoples are appropriated. The emperor Heraclius cut soldiers' pay by half in 616, and proceeded to debase the currency. The Roman and Byzantine case studies illustrate different outcomes to complexification, and offer different lessons for understanding sustainability.
