My wife and I were at a wonderful birthday celebration yesterday for a dear family friend, and the party was filled with many friendly faces, some of whom I had not seen for a while.

Among those faces was a man, who is now an accomplished and highly-regarded lawyer. I interacted with him in a professional sense about 20 years ago. At that time, he and I worked closely together over a period of about six months. We spent some time together, and I got to ask him lots of questions during that time. I don’t think about that time of my life often anymore, but every time I do, I think of him fondly. He was smart, competitive and a great guy.

When we ran into each other yesterday, it became a wonderful opportunity to catch up with the old days. We spoke a lot about the life 20 years ago. We also talked about kids, family and updates on professional pursuits... all the usual stuff. After seeing him, the memories of that time came back vividly. At that time, we were working together on the preparation for a case he was going to handle. We had many conversations about how to prepare for the case. And how he and I got through the difficult period came to my mind immediately.

On the way back home from the party, I thought about the many conversations we had. And then I remembered that he had sent me a book that he said was very important to him but unfortunately, I placed it in the basement without reading. So when I got home, I went into the basement, where I kept all sorts of things from my life.

And thankfully, I was able to find the book.

Immediately, I found his address and drove to his home.

Silk was invented in China in 3000 BC. It was well integrated into the Chinese economy during the Han Dynasty,     1     plain silks and products of peasant households were used as the main form of tax paid to the government. Fancy silk clothes were worn by the wealthy     2     symbols of status from the Han Dynasty on.

Women played     3     major role in the production of this vital product. In many households, the laborious task of raising the silkworms (蚕) originally     4    (restrict) to women.

Producing silk is a     5    (relative) lengthy process and demands constant close attention. The worms need a certain degree of     6    (warm) to survive. Sometimes the tiny eggs were sewn into little cotton bags and worn beneath the clothes. When hatched (孵出), they might be placed in shallow baskets or on shelves in the house     7     fed fresh mulberry leaves night and day. When they became cocoons (茧), dipping them into hot water to loosen the tightly woven filaments (细丝) and then     8    (wind) these filaments onto a spool (线轴)     9    (produce) the silk threads woven into cloth were also     10    (woman) work. Today, silk factories still mainly employ women for these tasks.

10 . Most people believe that pencils are made from lead, but this isn’t quite true. They’re actually made of a mineral called graphite (石墨).

    1     During the late Middle Ages, in a village called Borrowdale, in England, a group of locals saw a few uprooted trees.     2     On e of them had the idea that this dark substance could be used to mark sheep so owners could record and track them. This discovery by those curious locals paved the way for the modern pencils.

You may wonder why solid graphite can leave its color behind.     3     Graphite is made of carbon layers. When we use it as a pencil, the carbon from the pencil rubs off and gets deposited(沉淀) onto the fibers of the paper. These deposited pieces stick to the fibers of the paper and firmly remain there.

    4     You could stain your clothes and make your hands dirty. Later, people came up with some ideas. For example, in the late eighteenth century, an officer in Napoleon’s army designed the wooden pencils we see today. He roasted a mixture of water, clay and graphite at about 1,900 °F. After this mixture cooled down, he put it within a long wooden covering. This is how the wooden pencil came into being.

When you want to remove your writing, you need to turn to an eraser. The functioning of an eraser is based on a common principle. Erasing happens because of the friction that develops between the eraser material and the paper. When you rub an eraser on the paper, the resulting friction can produce heat, which helps the eraser become sticky, stickier than the paper.     5