15th Century: Johann Gutenberg (c. 1395-1468)

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And that was only the beginning of a tide of print that has been rising ever since. We can hardly imagine a world without an abundance of printed matter, and thus we take for granted an invention that produced astonishing consequences. Early printed books tended to resemble, in appearance as well as content, the hand-copied manuscripts they were replacing. The dissemination of the writings of Greek and Roman authors led to a revival of the classical learning that spurred the Renaissance. Printed religious texts put the word of God directly into the hands of lay readers. Such personal contacts helped fuel the Protestant Reformation.

Before print, the ability to read was useful mainly to the elite and the trained scribes who handled their affairs. Affordable books made literacy a crucial skill and an unprecedented means of social advancement to those who acquired it. Established hierarchies began to crumble. Books were the world's first mass-produced items. But most important of all, printing proved to be the greatest extension of human consciousness ever created. It isn't over: the 500-year-old information revolution continues on the internet. And thanks to a German printer who wanted a more efficient way to do business, you can look that up.

--By Paul Gray