I do a lot of public speaking on sustainability, but my very first speech after The Triple Bottom Line appeared in print over a year ago is still the most memorable--not for the speech itself, but because of what happened afterwards.

I was running late for the airport and my cab was waiting in front of the hotel. Before I could sit back, the cabdriver asked: "How was your speech?" I looked up and saw, looking at me in his rear view mirror, an older cabbie with a scraggly goatee and a cloth cap.

I asked him how he knew I had been giving a speech, and he told me that the hotel concierge had told him. "What was it about?" he asked.

Hmmm, I thought, how to explain this? "Well, I am an expert on something called sustainability. It's about how companies are expected to do more than just make a profit, and I was speaking about how profits can actually be increased by good social and environmental performance."

He didn't reply, so I tried again.

"Sustainability is about how companies can do the right thing and make money at it."

He still said nothing.

Instead, he reached over into the front passenger seat, and, without taking his eyes off the road, handed back to me a fifteen-page, single-spaced manuscript entitled Sustainable World.

"Read this," he said. "I wrote it three years ago and have given out over 1,700 copies from this very cab."

Huh? The first paragraph began with a quote from the UN Commission On Our Common Future. As I read it, I had three thoughts.

The first one was: "Am I on Candid Camera?"

If you're too young to remember, Candid Camera was a TV show from the 1960s that featured practical jokes played on unsuspecting victims--an early form of reality television. Laugh if you will, but I have three jokester brothers, and it seemed entirely possible that one or all of them had hired an actor and rented a cab to do this to me on my maiden voyage.

I actually accused the cabbie of this. I really did. He assured me he was on the level and had never met my family.

As this sunk in, my next thought was: "Wow, do I have the right book at the right time, or what?"

And then, as I continued to read his highly articulate tract on what companies, governments and NGOs needed to do to save the world, a final and more somber thought occurred: "This guy is a competitor of mine. And at the moment he's 1,600 copies ahead of me."

In hindsight, I realize that the second thought is the most important one. When cabbies are talking and writing about sustainability, can real change be far behind?