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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.

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Why not create something out of crumpled paper?

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