The Printing Press (1440)

The printing press is history's most transformative knowledge tool, slashing book production costs by 90%—a single press could produce 3,600 pages per day, surpassing a scribe's 2–3 pages by over 1,000-fold. This radical affordability enabled mass literacy, with 20 million books printed in Europe by 1500, triggering the Protestant Reformation and accelerating the Scientific Revolution. Outperforms #2 the Internet in transformative historical impact over a century, creating literate publics where none existed before.