Gutenberg - The Man
Gutenberg was a goldsmith from Mainz who never signed his work. Theories abound as to his life. Some historians speculate that he was a brilliant inventor who died penniless, and others believe he was eventually rewarded by the Archbishop of Mainz and carried on printing until his death. 
Paul and Blaise believe that Gutenberg saw his talents as a divine gift, so it wasn't for him to sign his work, there being a more powerful Creator behind it. 
Around 1430 Gutenberg left Mainz for Strasbourg where he was involved in a number of activities that show him as a bit of an entrepreneur. He was paid to teach people the art of polishing semi-precious gemstones. He was also in partnership with men who produced tokens to be used during pilgrimage. 
Financial and legal records are the only way of tracking Gutenberg. They show that he was part of a group that disputed his father's will around 1420. He drew a form of life insurance payment from the city of Mainz, but there were problems over that, and he was sent into exile for political/economic reasons. There are tax records to show how much he paid for wine in Strasbourg. He was sued by a woman who claimed that he had promised to marry her. But very little is known about his invention as there are no records. The invention itself did not form part of taxable income, so it does not appear in taxation records. 
The most significant record is a court document that records a dispute between Gutenberg and his business partner over the huge amount of money required for his printing press. Another document, dated just after Gutenberg's death in February 1468, is from a powerful citizen who recorded that he was then in possession of type and other equipment left at Gutenberg's death. 

What is the printing process and did Gutenberg invent it?	
The printing process using woodblocks were first used during the Sui Dynasty in China ( circa 581) and became popularised in the Tang Dynasty (circa 618). 
A system of printing from movable metal type was developed in Korea using Chinese characters a generation before Gutenberg's invention. A commoner by the name of Bi Sheng used movable-type blocks for printing during the Qingli years ( circa 1041) of the Northern Song. 
But there's no evidence of a transmission of technology from Korea to Western Europe. 
Invention requires putting together disparate elements in a novel way, making a cohesive, coherent process that can then be carried on by many different people. It was Gutenberg's combination of the printing press, type, paper and ink that made the invention a success.
The printing process credited to Gutenberg involved creating a mould or matrix. A letter, carved back to front on a metal punch, was hammered into copper, creating a mould or matrix. This was then filled with hot metal, which cooled down to create a letter. The matrix could be reused to create hundreds of identical letters. These letters were then placed on a rack, inked and, using a press, endless copies could be made. The letters could be reused in any combination, earning the process the name of 'movable type'. 
But no accounts have been left to prove that this was the method that was first used and no tools survive.

Discovery
Using computer software, Blaise Aguera y Arcas and Paul Needham analysed Gutenberg's work to try and identify the tools he used to create them. To their surprise, they discovered every letter was different, casting doubts on his methods.	
Paul and Blaise started their research with work done in the 1960s by Charlton Hinman. He completed a comprehensive analysis of Shakespeare's First Folio, comparing the differences in type setting between different copies, including the identification of broken and damaged types. He was able to determine the sequence of printing, of corrections that were made in press, and re-settings. This gave an insight into the way in which Shakespeare wrote his plays and the order in which they were amended. Hinman used a device based on a machine for analysing aerial photographs from the Second World War. 
Gradually Paul and Blaise came to realise that, rather than developing a method of dating books, they had unearthed a fundamental flaw in our assumptions about Gutenberg's printing methods. 
Doubts about what Gutenberg invented had been expressed before. Among the sceptics was Fournier Le Jeune, a printer and type founder in the 18th century, who examined some early Gutenberg printing and concluded that it wasn't printed from type cast with a reusable matrix. He'd noticed irregularities and believed that the documents were printed from wooden types that were carved individually. That has since been disproved. 
