How did people see before eyeglasses were invented? Probably not very well. Of course, several thousand years ago, most people didn't need 20/20 vision. They were farmers, shepherds, and laborers. They didn't drive down busy freeways or read the daily newspaper. In fact, most people could't read and write at all.
In places such as ancient Greece and Rome, messengers announced the news out loud in city streets. Noblemen sometimes hired scholars to read books to them. But there weren't many books to read anyway. Printing presses didn't exist. Scholars had to copy books by hand.
Even presbyopia, the failing eyesight of old age, didn't bother all that many people thousands of years ago. Medical knowledge was limited, and most people didn't live much past age 45.
Seneca, a first-century Roman leader and author, knew how to read, but he didn't have good eyesight. So he came up with a trick. He read books while looking through a glass jar filled with water. The jar of water acted like a magnifying lens, enlarging words on the page. Seneca didn't know that a lens made of clear crystal or glass, if cut to the right shape and thickness , would magnify images the same way.
Part 2. Experiments and Observations
