The church as a catalysis for scientific and technical discoveries? Hard to believe? Yet many inventions were made by monks, priests and clerics who toiled and researched alongside their prayers and sermons, sometimes, but not always, with the consent of their superiors. Using lucid though and razor-sharp logic it is possible to defeat theological opponents in discussions, but also invent black powder, follow the course of the planets, discover sunspots and predict eclipses, devise mathematical symbols and give the world such useful inventions as the abacus, washing machine, slow-motion photography and reader's letters - all the work of the clergy.