In 1450, all Europe's books were hand copied and amounted to only a few thousand. By 1500 they were printed, and numbered in their millions. The invention of one man — Johann Gutenberg — had caused a revolution. Printing by moveable type was a discovery waiting to happen. <br><br>Born in 1400 in Mainz, Germany, Gutenberg struggled against a background of plague and religious upheaval to bring his remarkable invention to light. His story is full of paradox: his ambition was to unite all Christendom, but his invention shattered it. He aimed to make a fortune, but was cruelly denied the fruits of his life's work. Yet history remembers him as a visionary. His discovery marks the beginning of the modern world.