The apocalyptic scenes John conjured in his writings formed a memoir from the front line of the first global pandemic in recorded history. A form of bubonic plague caused by the bacterium Yersinia pestis, spread by fleas that hopped between small mammals, black rats, and human beings, the disease slashed its way across all three continents of the known world in the middle of the sixth century a.d., ravaging sub-Saharan Africa, Persia and the Middle East, China and central Asia, the Mediterranean coastal bowl, and northwestern Europe.
