For twenty years, I saved all my college course notes and textbooks: that's a lot of paper.  Worse, it wasn't easy to carry them around—and trust me, they weren't light — on at least seven moves. Yet I never once looked at them. They sat in our basement, covered in a thick layer of dust. If books and papers could wonder, they'd wonder why they were still under our stairs after all those years. What were my plans for them? When would the Big Day come?

    Well, the Big Day eventually did arrive; only it was different than expected. My wife, always more accepting changes than I am, finally convinced me to clear out the entire mess.

    The pain I experienced was also unexpected. I didn't feel nostalgia(怀旧的), or suffer pains for long-lost magical moments of my education. No, what hurt me was to come across those terrible papers I'd written, reminders of poor study habits, immaturity(不成熟), and an embarrassing lack of comprehension. It was great to get rid of them. I won't have to carry those dusty, filthy(脏兮兮的) things on our next move. But it was also a clearing of personal history. Initially, I struggled with this. My books, my notes, and my papers were primary source materials, documenting an important time in my life. To clear them out was to clear out the truth. What I've learned since taking this leap is that the lesson is more important than the truth. I feel as if much of my real education during my college years isn't in the documents but now in me. So I am glad to free myself of this physical burden of carrying them around. And what's better is that I don't need to look back on those painful moments. They belong to the past.

    You might want to consider doing something similar, either under the stairs of your basement or in your mind. Not so long ago, a very smart person created a new holiday—Discardia!—to be celebrated four times a year. It's a great idea, and every time I clear things out, I feel better physically and psychologically. Discardia's slogan is “Let go of everything that doesn't make your life awesome!” What is the personal rubbish piling in your life? Clear it out and make your life awesome.

    These days, North Kickapoo Street in Shawnee, Oklahoma, is a four-lane road leading out to the highway, and lined with all kinds of places to eat and shop. But in the mid-1950s, it was just a gravel(砂砾) country road, the perfect place for our daddies to teach us how to drive.

We didn't have driver's education at Shawnee High School. We were on our own. Mom took me to pick up an instruction handbook. I was the oldest of my friends, so we were excited at the prospect of a whole new world opening up. We'd have freedom to get around. Best of all, we could go to the Starlite Drive—In theater on 50-cents-a-carload night. We'd have it made.

    Mom let me back our 1949 Ford out of the garage a few times to get used to the clutch (离合器) and gearshift (变速排挡杆). I got familiar with the motion but was hardly ready for my road test.

    Finally, the day came for Daddy to give me a real lesson. He drove out to the end of the paved section of Kickapoo Street and across to where the gravel started. My daddy had come from a family of 10, and they had been farmers in a poor area in Oklahoma. There was only one way to do things, and that was the right way.

Praises were rare, so when he expressed his approval it was special. I didn't want to experience his glare if I ground the clutch or the car shook as I tried to get it going.

    I took a deep breath, slowly let out the clutch, pushed the stick into second gear, eased down the road, and then carefully moved into third gear. He had me stop and repeat the procedure two or three more times until I came to the end of the section. I was feeling pretty good as I came to a stop and looked to Daddy for approval.

He glared at me and then barked, “You've been driving, haven't you?” He must have thought I'd been practicing in somebody else's car. I quickly explained that my training was all done on the Ford.

    That was 60 years ago. I can still see the nod he gave me when he said, "Well, you did a good job."

    Last summer, bird-watchers confirmed the discovery of a new species of bird in Cambodia was not an event of particular biological significance, but it was striking for one reason in part. This species of bird was discovered not in an unspoiled rain forest but within the limits Cambodia's capital, Phnom Penh – a city the size of Philadelphia.

What the researchers found was surprising in cities. The medium-sized city in the state about 110 species of birds, over 95 percent of which would have been growing there urbanization. Ecologically speaking, cities are different, concrete buildings. Rather, each unique bio-profile – a kind of ecological fingerprint – that is against the idea of an environment dead zone.

    Of course, it's also true that in the world of birds and plants, as in human society, there is such a thing as worldwide—the city-inhabitants who feel equally at home in San Francisco, Milan and Beijing. Four birds occur in more than 80 percent of the cities studied, and 11 plants occurred in more than 90 percent of the cities. On the plant side, those are seemingly spread by European settlement. In the air, it's the usual suspects: the rock pigeon and many other birds. “They have become completely adapted to urban life,”Katti says. “That's not much of surprise. But they don't actually dominate as much as we think they do.” Those species—occurring in the cities across the globe—represent only a small part of a city's natural varieties.

    Not all cities are equal protectors of native animals and plants, though. One of the biggest predictors for a city's biodiversity is its urban design. Territory as varied as backyards and street trees can lay important roles in greening a city. In fact, the amount of green space is a stronger predictor of the density of biodiversity than a city's size. A metropolis with a sizable network of parks can contain more species per square mile than a much smaller city.

    In a world where architecture, food, language, fashion and commerce are increasingly globalized, a city's native animals and plants can be a kind of identity. There may be neighborhoods in London and Paris that resemble Singapore or Hong Kong. Cities are becoming similar, but their natural environments stand completely apart.

    On the eve of our daughters' weddings, I gave both of them what I considered to be excellent marital advice: never leave your husband unsupervised （无人监督的） with pruning shears （修枝剪）.

    If only I had taken my own advice. I recently let my guard down. Thirty﹣some years of marriage can do that to a woman. Give a man pruning shears and electric trimmers （电动修剪器） and he will give new meaning to "armed and dangerous."

One day earlier this year, my husband said that the crab apple tree was dead.

    "Why do you think it is dead?" I asked.

    "Look at it. There's not a leaf on it."

    "There's not a leaf on anything. It's March," I said.

    "It looked sick last fall and with this bitter winter we had, I'm convinced it's dead."

    The truth is he's never liked the crabapple. Sure, it has beautiful blooms in the spring, but then it gets a disease, the leaves curl, and it drops those little apples that sit on the driveway.

    Each passing week he pronounced the tree dead. Eventually I began to believe him. Though he agreed it would be a regrettable loss, there was a twinkle in his eye. He armed himself a couple of weeks ago and began trimming. A branch here, a branch there, a small limb, then a large limb. I watched and then decided to check the wood on some of the branches closer to the trunk. I broke one off and saw green.

    The crabapple was not dead. It just hadn't had time to leaf out. The tree was now falling to one side, but it was not dead. I would have told him so, but he had moved on to a maple. Once the man starts, he can't stop. One trim leads to another.

    "Please, stop!" I called.

    He smiled and nodded, but he couldn't hear because he had started the hedge （树篱） trimmers and was getting ready to fix a line of hedges.

    Zip （飕飕声）, zip, zip.

    "What do you think?" he shouted.

    "It's supposed to be a privacy hedge; now all that will be private are our ankles."

    He started the trimmers again.

    "Stop!" I called, "Come back!"

    "Why?" he shouted.

    "You're in the neighbor's yard."

    I was deeply moved by the kindness of an elderly flower seller at Sydney's Central Station one evening.

    I was feeling as cold as the winter winds quickening the steps of the people who buried chins (下巴) in scarves and hands deep into coat pockets. In many ways, 2018 had proven an arduous year. My teenage daughter had left home for university, my job of 23 years was no more, and a creative project I'd given my all to for years had also been suddenly called off. I also found out a person I considered a friend was far from it.

    A year earlier, I'd dreamt about an earthquake. In the dream, a red light flashed inside a building and then the earth began to rock. Walls fell down on me as I ran into the open, feeling sorry for the people I hadn't loved enough. Before I was buried completely by the falling world, I shouted, "Abuelo, ayudame," in my native Spanish. "Grandfather, help me!"

    Now, with the very real aftershocks of a series of unexpected endings, I walked into a little flower shop to buy a gift for a friend. The gentleman at the shop looked at me and turned away for a moment, returning with a fragrant flower. "For you. You need to smile today," he said in a rich and beautiful accent, offering me the flower with eyes full of care. It took all my strength not to cry. Then he gave me a grandfatherly hug that made me want to tell him everything.

    Instead, I thanked him and headed for the train. How did he know? I wondered. For the first time in weeks, I felt hope.

People have long watched moths （飞蛾） and other flying insects flock to streetlamps, lights and flames. These insects appear attracted by the light. But a new study suggests they may just lose track of which way is up.

Previous theories say light probably blinds flying insects so that they get trapped by the light, or maybe they interpret light at night as a place to fly for a quick escape. Now the new study suggests flying insects instead turn their backs to the sky's light to keep their feet pointing toward the ground. Insects naturally turn their backs toward light. But when that light is from an artificial source, it may affect their sense of direction, leading to them flying in circles or diving toward the ground.

At a field station in Costa Rica, Samuel Fabian, an entomologist from Imperial College London in England and his teammates set up hanging and standing lights, and then used high-speed cameras to track wild, flying insects including moths and flies. Some circled the lights endlessly, and others flew sharply upward, losing speed until they couldn't fly any higher. When the light source pointed up, some insects turned around and headed for the ground. During the flight, the insects always kept the lights at their back even if they'd end up crashing. Crash landings were common when the team lit up a white sheet on the floor. But not when a white sheet—stretched into a height above the floor—was bathed in diffuse （漫射） light, much as the sky would be, insects flew through the area without getting trapped by the light.

The team also observed some species in a lab. Moths and dragonflies generally behaved like the wild insects, and they kept the light at their backs. However, in the lab, fruit flies, like oleander hawk moths—which can fly in the dark—could fly over LED lights without being thrown off course. In the wild, though, the moths still crashed. Maybe this is because, Fabian says, the insects can sometimes control their response to light, or over time, they might learn to avoid artificial light.