3 . Like most of us, I try to be mindful of food that goes to waste. The arugula (芝麻菜)was to make a nice green salad, rounding out a roast chicken dinner. But I ended up working late. Then friends called with a dinner invitation. I stuck the chicken in the freezer. But as days passed, the arugula went bad. Even worse, I had unthinkingly bought way too much; I could have made six salads with what I threw out.

In a world where nearly 800 million people a year go hungry, “food waste goes against the moral grain,” as Elizabeth Royte writes in this month’s cover story. It’s jaw-dropping how much perfectly good food is thrown away — from “ugly” (but quite eatable) vegetables rejected by grocers to large amounts of uneaten dishes thrown into restaurant garbage cans.

Producing food that no one eats wastes the water, fuel, and other resources used to grow it. That makes food waste an environmental problem. In fact, Royte writes, “if food waste were a country, it would be the third largest producer of greenhouse gases in the world.”

If that’s hard to understand, let’s keep it as simple as the arugula at the back of my refrigerator. Mike Curtin sees my arugula story all the time — but for him, it's more like 12 bones of donated strawberries nearing their last days. Curtin is CEO of DC Central Kitchen in Washington, D.C., which recovers food and turns it into healthy meals. Last year it recovered more than 807,500 pounds of food by taking donations and collecting blemished (有瑕疵的) produce that otherwise would have rotted in fields. And the strawberries? Volunteers will wash, cut, and freeze or dry them for use in meals down the road.

Such methods seem obvious, yet so often we just don’t think. “Everyone can play a part in reducing waste, whether by not purchasing more food than necessary in your weekly shopping or by asking restaurants to not include the side dish you won’t eat,” Curtin says.

4 . Sometime in the early 1960s, a significant thing happened in Sydney, Australia. The city discovered its harbor. Then, one after another, Sydney discovered lots of things that were just sort of there — broad parks, superb beaches, and a culturally diverse population. But it is the harbor that makes the city.

Andrew Reynolds, a cheerful fellow in his early 30s, pilots Sydney ferryboats for a living. I spent the whole morning shuttling back and forth across the harbor. After our third run Andrew shut down the engine, and we went our separate ways — he for a lunch break, I to explore the city.

“I’ll miss these old boats,” he said as we parted.

“How do you mean?” I asked.

“Oh, they’re replacing them with catamarans. Catamarans are faster, but they’re not so elegant, and they’re not fun to pilot. But that’s progress, I guess.”

Everywhere in Sydney these days, change and progress are the watchwords (口号), and traditions are increasingly rare. Shirley Fitzgerald, the city’s official historian, told me that in its rush to modernity in the 1970s, Sydney swept aside much of its past, including many of its finest buildings. “Sydney is confused about itself,” she said. “We can’t seem to make up our minds whether we want a modern city or a traditional one. It’s a conflict that we aren’t getting any better at resolving (解决).”

On the other hand, being young and old at the same time has its attractions. I considered this when I met a thoughtful young businessman named Anthony. “Many people say that we lack culture in this country,” he told me. “What people forget is that the Italians, when they came to Australia, brought 2000 years of their culture, the Greeks some 3000 years, and the Chinese more still. We’ve got a foundation built on ancient cultures but with a drive and dynamism of a young country. It’s a pretty hard combination to beat.”

He is right, but I can’t help wishing they would keep those old ferries.

We all know that cycling is a greatly exercise. A doctor tells me people who lives the longest are dancers and cyclists. Maybe it is because the combination of fresh air, smooth movement and exercise. Whether you ride a bicycle, you don’t use petrol. So they are not producing carbon dioxide and not cause air pollution. Just see how cars have been taken over our cities. They often run at high speeds, what may put our lives in danger. And there were traffic jams, too. Our cities will be better places if we replace cars with bicycle.