If you could draw a graph showing the growth of mankind's knowledge and technology, you'd think it would look like a staircase, steadily edging upward year after year as we get a little bit smarter than our ancestors.
It's not true, though. Some of the most amazing things ever discovered wound up lost or forgotten for centuries, for utterly ridiculous reasons. Such as...
A whole lot of the modern world you're enjoying right now exists thanks to the invention of the steam engine, which kicked off the industrial age. It was invented in 1712 and later improved by James Watt, who would get all of the credit (right down to everyone using his last name to measure electricity).
Wait, did we say it was invented in 1712? Because that's actually off by 1600 years or so.
Some time in the first century, an engineer called Heron of Alexandria, or Hero to his friends, set to work on an aeolipile--a small, steam-powered turbine that propelled itself by shooting steam out of one or more orifices. Freaking 1600 years before the Europeans declared that the "new" steam engine would completely revolutionize the world.
How Could We Have Forgotten It?
It was too far ahead of its time. Think about it: This is a damned steam engine built during the era when the New Testament was going on. It would be like somebody making a prototype Warp Drive during World War I. No one could figure out what to do with it.