By 1450 Gutenberg, in Mainz, had invented the essential of modern typography: the mechanical reduplication of movable metal type. There is general agreement about the dates when printing began in various cities: 1454 in Mainz, 1458 in Bamberg and Strassburg, 1465 in Subiaco, 1467 in Rome, 1469 in Venice and Paris, 1470 in Utrecht, and 1477 in Westminster. It seems natural that so important an invention should have spread rapidly but, when we look at the data, several questions arise.
Why did so valuable a trade secret leave Mainz so early? Why in 1464 did three printers from Mainz— Konrad Schweinheim, Arnold Pannartz, and Ulrigh Hahn—cart their heavy printing presses over the Alps and the Apennines all the way to Rome? Why, once in Rome, did they then bring their presses (probably by ox cart) over mountainous roads to remote Subiaco, and there print the first books which were printed