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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.

One teacher had two students. One of them had a positive vision while the other had the 1 one.

One day, the teacher 2 for a park with both the students and while wandering in the garden, they 3 a mango tree from which some ripe and juicy mangoes were 4 . On seeing this, the teacher thought to 5 both of his students. Then, he asked the first one, "My dear child, what do you think of this mango tree?"

The student answered instantly, "Teacher, in spite of people 6 this tree with stones, it gives us sweet and juicy mangoes. It does 7 but still it gives us fruits. I wish all human beings learn this important 8 from the mango tree-to share their 9 even if they have to suffer for this."

After that, the teacher asked the other student the same question. The student 10 answered, "Teacher, this mango tree is no good and will not give mangoes by itself but only when we hit it with stones and 11 . Therefore, we should hit it hard to get sweet mangoes from it. That is the only way to 12 these mangoes. It is also clear from this tree that in order to get good 13 from others, we need to be violent and only when we become violent, then and only then will we get 14 ."

The teacher was delighted with the answer given by the first student because he had an admirable vision and 15 the tree with positive vision.

They talk about the straw that broke the camel's back, but really it should be the password that wiped out my memory bank. 

I was going along fine -with instant recall of my bank PIN (密码)，my mobile phone number and the date of my cousin's birthday before I downloaded a gas station payment app for its new customer discount. It asked me to create a password. When I typed in "gas 1", it was rejected for not being complex enough. I tried again: "IHateHearlessOilCompanies@". But that was too long and didn't include "at least one number". But here is the thing: as soon as 1 added the fresh password into my memory, I instantly forgot all the others. My brain had hit its limit for passwords. I now know nothing. 

I had entered some passwords in a notebook. Of course, I didn't write down the actual passwords, in case it fell into the wrong hands. Instead, I masked them in a way that only a family member could figure them out. For example, I combined my bank PIN with our postal code, then added it to a list of phone numbers. It would fool even Albert Einstein.

Maybe we need a system like the one we use to remember people's names. You know, you form an association between a person's characteristics and their name by whispering "Skinny George, Skinny George" in heart after meeting them. The risk is that, upon seeing him, you'll burst out the phrase. "Skinny George" might not mind, but it's possible "Boring Betty" will. As for remembering passwords as you change them, you could simply use the first and last letters of your favorite singer's greatest hits, together with the year of their release.

Maybe I'll try that one out- -but only after describing the system in the notebook. Then I'll hide it in a place so secret that I'll never remember where it is. 

Grief ran through the first decade of my career. I photographed stories about terrible topics: immigration, conflict, war. On the cover of my notebook in 2019, I wrote, "Discover the joy again." It was intended to remind me to play more.

Sometimes I'd get a rare assignment where I could breathe — for example, photographing an article on tea for an airline magazine. I took the job hoping to make interesting, almost movie images, but at the end of the day, I found I'd made nothing of the sort. Packing up my camera, I felt like a failure.

On the drive back to the hotel, I noticed heavy steam rising from a building up ahead. Arriving at the scene, I opened the car door — and realized it was a tourist attraction traditionally pulled by a steam engine. Then, out of nowhere, a figure ran toward me. I picked up my camera and quickly made three pictures. One was out of focus. One was poorly composed. But one worked.

When I submitted my pictures to the editor for the tea article, this one wasn't chosen to be published, but I knew it meant something to me. I had been looking for good luck in my own life. This photograph symbolized exactly that.

I was 27 when I first traveled to India after the sudden passing of my father. Over many months, with my best friend, I traversed India with no phone, with limited Internet, and with healing as my compass. I climbed mountains, swam in the sea, and lived in relief entirely.

As I learned to travel to some of the world's cities with the largest population, I began to see life with more color and magic. I permitted myself to walk aimlessly, with no goal but to observe, and each moment became a dance. If this journey taught me anything, it's that what comes next will bring its own magic.