NARRATOR：

Listen to part of a lecture in a history class.

FEMALE PROFESSOR：

So we've been talking about the printing press, how it changed people's lives, making books more accessible to everyone.

More books meant more reading, right?

But, as you know, not everyone has perfect vision.

This increasing literacy, um, in reading, led to an increasing demand for eye glasses.

And here's something you probably haven't thought of: This increased demand impacted the societal attitudes toward eye glasses.

But, first let me back up a bit and talk about vision correction before the printing press.

And, um, what did people with poor vision do, I mean, especially those few people who were actually literate, what did they do before glasses were invented?

Well, they had different ways of dealing with not seeing well.

If you think about it, poor vision wasn't their only problem, I mean, um, think about the conditions they lived in:[listing] houses were dark, sometimes there weren't any windows; candles were the only source of light.

So in some places, um, like ancient Greece for example, the wealthiest people with poor vision could have someone else read to them. [dripping with sarcasm] Easy solution if you could afford it.

Another solution was something called a "reading stone".

Around 1000 C.E. European monks would take a piece of clear rock, often quartz, and place it on top of the reading material.

The clear rock magnified the letters, making them appear larger, um, looks like what happens when a drop of water falls on something, whatever's below the drop of water appears larger, right?

Well, the "reading stone" works in a similar way.

But rocks like quartz, quartz of optical quality, weren't cheap.

Late in the 13th century, glass maker in Italy came up with a less expensive alternative—they made reading stones out of clear glass.

And these clear glass reading stones evolved into the eye glasses we know today.

So we're pretty sure that glasses were invented in about the late 1200's, well, over a hundred years before the printing press.

But it's not clear who exactly invented them first or exactly what year, but record shows that they were invented in both Europe and China at about the same time.

By the way, we call this "independent discovery".

Independent discovery means when something is invented in different parts of the world at the same time and it's not as unusual as it sounds.

You can look at the timeline charts at the back of your textbook to see when things were invented in different cultures at about the same time to see what I'm talking about.

So now let's tie this to what I've said before about societal attitude towards glasses.

Initially in parts of Europe and in China, glasses were a symbol of wisdom and intelligence.

This is evident in the artwork from the period.

European paintings often portrayed doctors or judges wearing glasses.

In China, glasses were very expensive, so in addition to intelligence, they also symbolize affluence, um, wealth.

In 14th century Chinese portraits, the bigger the glasses, the smarter and wealthier the subject was.

So glasses were a status symbol in some parts of the world.

Now let's go back to the invention of the printing press in 1440.

What happened? Suddenly, books became readily available and more people wanted to read, so the need, oh well, actually not only the need but the demand for more affordable glasses rose drastically.

Eventually, inexpensive glasses were produced, and then glasses were available to everyone.

People could purchase them easily from a traveling peddler.