"Prophecy, Alchemy and the End of Time: John of Rupecissa in the Late Middle Ages" by Leah DeVun.
Columbia UP 2009.
ISBN 9780231145381
256 pages.
"Religious figures who preached the end-times were hardly rare in the late Middle Ages, but Rupecissa's teachings were unique. He claimed that knowledge of the world, and alchemy in particular, could act as a defence against the plagues and wars of the last days."
