Johannes Gutenberg invented the Printing Press (movable type mounted in a large press) in 1450 AD. The first 50 ears of printing are called Incunabula. 1501 ended the incunabula period of printing. By 1517 when Martin Luther started publishing his writings which changed Europe forever every town in Germany had a printing press. Luther was the first person to ever be recognized on the streets by his profile printed on paper.
Johannes Gutenberg was born circa 1395, in Mainz, Germany. He started experimenting with printing by 1438. Gutenberg's masterpiece, and the first book ever printed in Europe from movable type, is the “Forty-Two-Line” Bible, completed no later than 1455. Gutenberg died in Mainz in 1468.
A printed “leaf” is a single piece of paper from a book usually printed on both sides. Below are photos of four such leaves in my possession.