The Mechanical Industrial Revolution of the 13th and 14th centuries waned with "The Black Death" (bubonic plague), peaking in 1348. The Black Death was caused by the dearth of cats to control the rat population. For centuries, the superstitious had killed cats, alleging them to be the "familiars" of witches. (Cats' eyes can catch any light in a dark room or cave, lighting up when nothing else does. Also, in cold climes, stroking a cat invokes static electricity, and the sparks scintillate in the dark.) One Pope even advocated exterminating cats. So, by the middle of the 14th century, the dearth of cats allowed the rat population to multiply to epidemic proportions. The rats carried fleas. And the fleas carried the Plague. In 5 years, the Plague killed 25 million, 1/3 of Europe's Population. In some regions, 50% of the population died in "The Black Death". Many regions lacked blacksmiths, coopers, wheelrights, other craftsmen.

Training had been oral. The Church now allowed more general reading of "pagan" books, initiating The Renaissance. (Tell this story to teen-agers who "want to work with their hands", but ask why they need reading skills!)

  (Hymn: "Let All Mortal Flesh Keep Silence")

  nocat pipes the rats through our Heartland,
  Ravaging our fields and our stores!
  nocat and the rats pipe the Black Plague,
  Blooming forth in boils -- bloody sores!
  nocat, rats, and Plague -- they pipe The Apocalypse Four:
  FAMINE, PESTILENCE, DEATH, AND WAR!