Like any other invention, the printing press came along and had an impact when the right conditions existed at the right time and place. In this case, that was Europe in the mid 1400's. Like many or most inventions, the printing press was not the result of just one man's ingenious insight into all the problems involved in creating the printing press. Rather, printing was a combination of several different inventions and innovations: block printing, rag paper, oil based ink, interchangeable metal type, and the squeeze press.
If one process started the chain reaction of events that led to the invention of the printing press, it was the rise of towns in Western Europe that sparked trade with the outside world all the way to China. That trade exposed Europeans to three things important for the invention of the printing press: rag paper, block printing, and, oddly enough, the Black Death.
For centuries the Chinese had been making rag paper, which was made from a pulp of water and discarded rags that was then pressed into sheets of paper. When the Arabs met the Chinese at the battle of the Talas River in 751 A.D., they carried off several prisoners skilled in making such paper. The technology spread gradually across the Muslim world, up through Spain and into Western Europe by the late 1200's. The squeeze press used in pressing the pulp into sheets of paper would also lend itself to pressing print evenly onto paper.
The Black Death, which itself spread to Western Europe thanks to expanded trade routes, also greatly catalyzed the invention of the printing press in three ways, two of which combined with the invention of rag paper to provide Europe with plentiful paper. First of all, the survivors of the Black Death inherited the property of those who did not survive, so that even peasants found themselves a good deal richer. Since the textile industry was the most developed industry in Western Europe at that time, it should come as no surprise that people spent their money largely on new clothes. However, clothes wear out, leaving rags. As a result, fourteenth century Europe had plenty of rags to make into rag paper, which was much cheaper than the parchment (sheepskin) and vellum (calfskin) used to make books until then. Even by 1300, paper was only one-sixth the cost of parchment, and its relative cost continued to fall. Considering it took 170 calfskins or 300 sheepskins to make one copy of the Bible, we can see what a bargain paper was.
But the Black Death had also killed off many of the monks who copied the books, since the crowded conditions in the monasteries had contributed to an unusually high mortality rate. One result of this was that the cost of copying books rose drastically while the cost of paper was dropping. Many people considered this unacceptable and looked for a better way to copy books. Thus the Black Death rag paper combined to create both lots of cheap paper plus an incentive for the invention of the printing press.
The Black Death also helped lead to the decline of the Church, the rise of a money economy, and subsequently the Italian Renaissance with its secular ideas and emphasis on...