After the cold spell that allowed the Bubonic plague to climb down from the upper Nile River Valley to the Mediterranean world, that reliance on rapid transport across the Med turned from a blessing into a curse ... and undermining Justinian the Great's reconquests of North Africa, Iberia and Italy (guess who recently read Justinian's Flea?) ...
... but then after the collapse of that system emerged the North Atlantic economy built on the heavy horse-drawn moldboard plough and the three-field system, and the growth that followed from that was positive sum growth as well. Utsukushikereba sore de ii
