I blame myself for getting into the taxi in the first place. I had written a mental note to myself the night before, reminding me to go to the ATM before heading off to work. I was distracted by my increasingly frantic search through my wallet and pockets for any notes or coins to pay the fare as we cruised along.

When that failed to rustle up the necessary readies, I began phoning friends to see if they could meet the taxi and hand me the relevant cash.

Then I spotted the meter had already turned to 30 yuan ($4.60) for what is generally an 11 yuan ride. I was in a part of the city I didn't recognize. To my bemusement, neither, it seemed, did my driver.

I repeated my destination to the driver and he nodded his head, saying it back to me, but not convincingly. Clearly he was as lost as I was. Then he started asking me for directions.

This seemed to be the classic example of a farmer borrowing his urban brother's cab for a day to make a few extra kuai and trusting to luck with Beijing's sprawl rather than relying on a keenly studied knowledge of the map. At best it was betraying an enviable equality of opportunity among the taxi driving ranks, ignorance being no bar to entry to this essential profession.

I wasn't going to blame my Mandarin or my pronunciation: It was a journey I take five days a week and it had only gone wrong once before.

My previous experience of a failed traveling experience had been with a plump female driver who started laughing the moment I got in the vehicle, guffawed even more when I spoke, drove a few meters in hysterics, pulled up, still in stitches, switched off the engine and sat there, shoulders heaving in mirth.

I got out and hailed another cab, still baffled at what might have set her off, but with a lurking uneasy feeling that I am a laughing stock, and most people are too polite to let it show.

Not that taxi driver, though. She's probably still laughing now.

I asked my geographically challenged driver to pull up, tendered my meager collection of notes and coins, bade him a bad-tempered goodbye and set off in search of an ATM. To my relief he didn't argue. It was now raining and I didn't have a coat or umbrella.

As I trudged along the damp streets, I got to thinking about how much store we put in having a predictable future. If my day had gone according to plan I would have been tucking into a nice, hot meal, warm and dry in a restaurant, happily contemplating what the day held ahead on the work front and debating with myself how to spend what would be left of the evening.

But it's not just the trivialities of life with which fate dabbles. A missed appointment can lead to a job not being offered, another job taken, a whole new career opening up through which one meets a partner, buys a house, has children and creates a world of opportunity, chance and decision-making that defines their fate.

How many unexpected twists and turns are there in a lifetime that steer one to the inevitable end, and how many different lives could one have lived had one taken this decision or that, been pushed down here rather than there, been given a different set of genes that affected our intellect and looks?

It's impossible to answer such existential questions. We can but wonder, daydream and hazard guesses.

The uncertainty is unsettling. It goes against our inbuilt need for security, a desire for our lives to possess a certain degree of predictability. It's one of the reasons, many theologians argue, that turns people to belief in a divine being, something that suggests purpose in whatever form mankind wishes to postulate.