“I can't see clearly, because I don't wear my glasses today.” We always hear people saying something like this. Glasses are very important to many people. Do you know how they were invented and developed?

    Glasses took a long time to develop into what you can find in the glasses store today. The Chinese first used colored glasses as fashion. They thought that those glasses had magic, but they didn't think that glasses could help eyes to see clearly.

    In 1262, the inventor, Roger Bacon, discovered the amazing function(功能) of lenses(镜片), and he thought that glasses could be used to help people to see. Twenty years later, in Florence, Italy, the inventor, Alessandro di Spina, made the first pair of glasses that could help people to see.

Although these glasses worked, scientists didn't understand how glasses helped eyes to see. They thought that eyes sent out light onto whatever a person was looking at, and then the light came back to the eyes. Johannes Kepler finally found out how glasses worked.

Inventors continued to improve glasses. In 1784, Ben Franklin created glasses that had bifocal(双焦的) lenses. Many years later, in 1827, George Airy made circle-shaped glasses to correct astigmatism, an eye problem that stops the eyes from seeing things clearly.

    As we know, there are differences between western culture and Chinese culture. We can see differences when we pay attention to the way words are used. Let's look at the words about animals and plants. Most expressions in Chinese about dogs, for example, a homeless dog, a mad dog and a dog catching a mouse, have negative meanings. But in western countries, dogs are thought to be honest and good friends of humans. In English, people use the dog to describe positive actions. For example, you are a lucky dog means you are a lucky person. And every dog has its day means each person has good luck sometimes. To describe a person's serious illness, they say sick as a dog. The word dog-tired means very tired. However, Chinese love cats very much. But in western culture, cat is often used to describe a woman who is cruel.

    The rose is regarded as a symbol of love in both China and some western countries. People think the rose means love, peace, courage and friendship. And the rose is the national flower of England, America and many other countries.

    The words about plants and animals are used in positive or negative ways in different cultures. We can learn about many differences in cultures by comparing how some words are used.