Like many entrepreneurs, Gutenberg lived in turbulent times, building his major innovation incrementally.

In the 15th century, religious, political and economical change was brewing in Johannes Gutenberg’s hometown of Mainz, Germany. In addition to a power struggle between the emerging middle class and the old aristocratic families, the city itself was drowning in so much debt that creditors forced it to take austerity measures.

As we know today, such periods of change and disruption often spawn entrepreneurs.

At the age of 40, Gutenberg, a goldsmith, embarked on his first venture, which was perhaps less grandiose than one might expect: manufacturing and selling small mirrors to pilgrims. This endeavor was financially fairly successful, but, more importantly, it taught him crucial startup skills: how to recruit a team, set up a legal structure and raise funds.

You see, Gutenberg had bigger dreams than vending trinkets to pilgrims. In secret, he was developing the invention he’s remembered for today: the printing press.

This new technology required massive innovation, improvement and optimization on many fronts.

For one, the type needed to be cast from molten metal. Here, Gutenberg’s invention of a versatile mold and the right mixture of metals helped achieve a previously unheard of production pace; a single foundry worker could cast up to 3000 letters a day. This greatly sped up the printing process.

Another key technological innovation was the press itself, which Gutenberg modeled after the contraptions used in wineries, thereby vastly increasing printing precision.

Meanwhile, finding the right ink also took some innovation; Gutenberg mixed it from soot, amber and linseed oil to produce that rich dark tone still common today.

Developing and fine-tuning all these components took nearly 20 years, so you couldn’t say Gutenberg owes his fame to a sudden flash of innovation.

Of course, like any good tech entrepreneur, before launching his final product, the Latin Bible, Gutenberg started with a prototype, a beta-version, in the form of a Latin grammar book.

The book was downright ugly, its pages crammed tight with words; it proved, however, that the press worked.