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With the completion of the Human Genome（基因组）Project more than 20 years ago, and the discovery of the double helix structure of DNA enjoying its 70th birthday last year, you might assume that we know how life works. Think again!

Evolution has a 4bn-year head start on us. However, several aspects of the standard picture of how life works-the idea of the genome as a blueprint, of genes as instructions for building an organism, of proteins as precisely tailored molecular（分子）machines and more-have wildly reduced the complexity of life. 

In the excellent book How Life Works, Philip Ball explorers the new biology, revealing life to be a far richer, more delicate affair than we have understood. Ball explains that life is a system of many levels-genes, proteins, cells, tissues, and body modules-each with its own rules and principles, so there is no unique place to look for an answer to it. 

Also, How Life Works is a much more appealing title than the overused question of "What is life?". We should be less concerned with what a thing is, and rather more focused on what a thing does. Defining a living thing implies an unchangeable ideal type, but this will run counter to the Darwinian principle that living things are four-dimensional, ever changing in time as well as space.

But it's an idea that is deeply rooted within our culture. Ball points out that we rely on metaphors（比喻）to explain and explore the complexities of life, but none suffice. We are taught that cells are machines, though no machine we have invented behaves like the simplest cell; that DNA is a code or a blueprint, though it is neither; that the brain is a computer, though no computer behaves like a brain at all.

Ball is a terrific writer, pumping out books on incredibly diverse subjects. There's a wealth of well-researched information in here, and some details that are a bit chewy for the lay reader. But the book serves as an essential introduction on our never-ending quest to understand life.

Lily loved school. However, there was one class Lily worried about more than any other—art. She didn't know why she just wasn't any good at drawing, painting, or cutting.

Ms. Clay, the art teacher, stood at the front of the room. "Class, next Friday our school is going to have an art competition," she announced. Ms. Clay was a great teacher, and Lily liked her a lot. But this announcement made Lily nervous. "Everyone in the school will create a piece of artwork to show in the library. You can use the different types of artwork we have been studying." Ms. Clay was quite excited when she spoke while Lily found herself sinking lower in her chair.

Lily had the whole weekend to work on her project, but she could not think of anything to do. On Monday, Lily felt frightened, so after school Lily asked Ms. Clay if she could write an art paper instead of doing an art project.

"I understand this project scared you, Lily," Ms. Clay said. "Just remember, you can create any kind of art you want." Ms. Clay smiled at her. "Art is a person's way of expressing his or her feelings—it isn't always painting, drawing, or cutting. I know you will think of something very creative, and I can't wait to see it."

When Lily arrived home, she took out a piece of paper and a pencil. She remembered Ms. Clay's words. "Art is a person's way of expressing his or her feelings." Lily wrote the word "terrified" on her paper. She crumpled (揉皱) the paper and threw it to the side of her desk.

Then Lily stared at the crumpled ball. Suddenly an idea struck her.

Paragraph 1：

Why not create something out of crumpled paper?

Paragraph 2：

On Friday, Lily carefully carried her project into the library.

Two men were sitting together in a plane. They were on a long journey. One of the men was a businessman. The other was a farmer. They sat without talking for a while, then the farmer said, "Let's do something to pass the time."

"What do you want to do?" the businessman asked. "We can ask each other riddles(谜语）." The farmer said, "You start." "Let's make the rules first," the businessman said. "That's not fair. You are a businessman with much knowledge. You know more things than I do. I am just a farmer."

"That's true." The businessman said. "What do you want we should do?" "If you don't know the answer to a riddle, you pay me $100. And if I don't know the answer, I'll pay you $50." The farmer said. The businessman thought about this, then he said, "OK. That's fair. Who will go first?"

"I will," The farmer said. "Here is my riddle. What has three legs when it walks, but only two legs when it flies?" The business man repeated the riddle, "What has three legs when it walks, but only two legs when it flies? Mm, that's a good one. I'm afraid I don't know the answer." He gave the farmer $100, then said, "Tell me the answer. What has three legs when it walks, but only two legs when it flies?" "I don't know." The farmer said and gave him $50.

Over the past 38 years, Mr. Wang has pretended to be someone else many times, and has even learn ed to 1 different dialects (方言), leading to him being described as an "Oscar-winning actor".

The 60-year-old is not an actor, but a 2 However, he is more devoted to his "3 " than any real actor. In the 1990s, a group of thieves often sold stolen goods with the help of some beggars. To look into the 4 , Wang disguised (伪装) himself and 5 the beggars.

Dirty clothes and old shoes gave him the 6 of a real beggar and his convincing dialect soon won him the 7 of the beggars. "I often 8 them to drink alcohol. Once they were 9 they began to talk a lot," Wang said. "I'd then 10 myself to use the toilet, 11 what the beggars said, and send the 12 to my teammates."

Wang, who is often in 13 situations, is also a judo (柔道) master. "As long as I get close enough, no criminal(罪犯)can 14 from me," he said. Wang's 15 won him several honors including a National May Day Labor Medal and 11 Citations of Merit. Paris. 

I was cutting up lettuce in the kitchen when I suddenly remembered watching a video about soaking the lettuce stub (莴苣残余部分) in water to grow a whole new vegetable. So I took out a wide-mouthed cup and placed the stub into it, gave it a little water, and placed it by the window. 

On a snowy morning I noticed the first sign. A first small leaf from its heart spread out. A tiny green flag of hope. Beaten, but not defeated. This lettuce was not done living! Within days, it was impossible to see the cuts where I had removed the leaves. The growth was explosive. And when I lifted the blossoming head out of the cup, tiny root threads fell down, seeking for the earth. 

What is growing here? Lettuce or hope? 

If I were a lettuce in a similar condition, I'd want to skeptically assess where I found myself before committing to full growth. Yet for this lettuce, my inadequate offering of water and a place by a window was enough for it to decide to reclaim itself again. It grew in a cup of water, in faith. This is the heart of this lettuce: alive, strong and fearless. It deserved a name. I decided to call it Monty. 

Monty wanted to grow, as we all do. I think I gave him a little love and freedom. Those two were all he needed to return to himself. I see joy in this lettuce. The return to self is always an expression of joy, which is life itself. This is the tendency of all living things. 

Monty still lives in a cup, but I'm going to transplant him outside. He deserves to become his full self. The only problem I see now is my ability to support Monty. I hope I have enough of a green finger. 

I'm surprised to find myself where I am. Maybe Monty is, too. I have the same choice as he does: give in or start again. The prospect of starting again is discouraging. But my lettuce-friend, Monty, leads the way. I can only hope to be as brave.

Faye and Matthew Gooding and their five young sons appear to have perfect lives. Mrs. Gooding 1 beautiful photos of life in their four-bedroom house on Instagram(一种社交软件), and more than 32, 000 people 2 them. For the couple themselves, 3 , this "materially(物质地) perfect world" was lacking something—so now they are giving up all their 4 to travel around the world with their kids.

This was the last Christmas that the couple spent in their house, which has already been sold. Most of their belongings are 5 too. Shortly their Ford car will be sold and the family will take just one backpack each.

Mrs. Gooding said: "Some friends and family think Matt and I are 6 to be giving up so much. It's been difficult giving up so many possessions. Yet 7 enjoying spending time with the boys, I found myself cleaning the house all day before. The older ones were at school and I thought, 'I 8 see them'. I admitted how I felt to Matt. He agreed it felt as if our lives moved around 9 things—both of us working to 10 the mortgage(贷款) and keep ourselves in our materially perfect world."

    They will leave this month and plan to start their 11 in Sweden where they have friends.

Mr. Gooding added: "People have said 'aren't you worried about stability and safety?'— 12 as we have five small children. It is a (an) 13 because we are giving up so much. But we can't wait to spend more time with our sons without the 14 of everyday routines. We don't know what will happen, but we do know if we didn't do this we would always 15 it."