In the summer of 2008 I enrolled in a German language class in Berlin. The school was a 40-minute ride by tram from where I lived. To save on travel expenses and to get some exercise, I bought a used bicycle at a flea market.

It turned out to be too small for me and the saddle was uncomfortable. After two weeks of torture I decided to sell it. An hour after posting an ad on a website, my phone rang.

The caller inquired about the condition, size and price of the bicycle. Her voice sounded so familiar, like that of an old schoolmate. We agreed on the time and place to meet and complete the transaction. Then she randomly asked: "How tall are you?"

"About 1.72 meters." "Are you Yuli?" I couldn't believe she called out my name!

I replied, "Are you Beiru?"

We were both right.

Even today that odd encounter seems like a miracle.

We had been college schoolmates, but didn't know each other well. We never had each other's phone numbers. I knew she had come to Berlin about a year earlier.

It had also been the first time I had ever used the website on which I posted the bicycle ad.

It was unbelievable!

We were both excited and surprised, but it didn't actually push forward our friendship. We did exchange cellphone numbers but never called each other. She didn't buy the bicycle, either.

When I looked back later, I realized that such coincidences bring little more than a momentary surprise. What are they for? Did God only set up all these occurrences for us to exclaim how small the world is?

I haven't figured it out, at any rate. More recently, another unusual incident happened.

My boyfriend and I moved into a new flat about eight months ago, and it's the best apartment we've ever lived in: bright, clean, spacious, high floor with gorgeous view.

One day not long ago I ran into an elder college schoolmate in the elevator of the building. He told me he also lived in the building, close to my floor, with his girlfriend - also a former schoolmate. They have also lived in their apartment for eight months.

If that time in Berlin I was pleasantly surprised, then this time I was shocked, but not so pleasantly.

I resent the fact that my schoolmates and I live in the same building. Same community, OK. Same building? Not good. We know each other, have participated in the same activities in college several times, but are hardly friends.

It's not that I don't like them. But I do mind living too close to them. Beijing is a super big city with hundreds of thousands of apartments. Why did such a coincidence happen again? I questioned myself: am I being too sensitive or stingy? When my boyfriend asked me whether we should renew the lease this year I said I would rather not. To be close to my workplace is one thing, to find another place with fewer coincidences is another.

I once read an article about a survey in which several people are seated on a park bench one by one. The second person normally chooses a spot far from the first person. But if that person sits too close, the first subconsciously shifts away. This experiment demonstrated man's strong need for privacy.

I don't know whether my former schoolmates, the couple, have the same confusion.