It was 1978. I was new to New York. A rich acquaintance had invited me to a housewarming party, and, as my cabdriver wound his way down increasingly potholed and dingy streets, I began wondering whether he'd got the address right. Finally he stopped at the doorway of a gloomy, unwelcoming industrial building. Two winos were crumpled on the steps, oblivious. There was no other sign of life in the whole street.

"I think you may have made a mistake", I ventured.

But he hadn't. My friend's voice called "Top Floor!" when I rang the bell, and I thought - knowing her sense of humour - "Oh this is going to be some kind of joke!" I was all ready to laugh. The elevator creaked and clanked slowly upwards, and I stepped out - into a multi-million dollar palace. The contrast with the rest of the building and the street outside couldn't have been starker.

I just didn't understand. Why would anyone spend so much money building a place like that in a neighbourhood like this? Later I got into conversation with the hostess. "Do you like it here?" I asked. "It's the best place I've ever lived", she replied. "But I mean, you know, is it an interesting neighbourhood?" "Oh, the neighbourhood? Well that's outside!" she laughed.

The incident stuck in my mind. How could you live so blind to your surroundings? How could you not think of where I live as including at least some of the space outside your four walls, some of the bits you couldn't lock up behind you? I felt this was something particular to New York: I called it "The Small Here". I realised that, like most Europeans, I was used to living in a bigger Here.

I noticed that this very local attitude to space in New York paralleled a similarly limited attitude to time. Everything was exciting, fast, current, and temporary. Enormous buildings came and went, careers rose and crashed in weeks. You rarely got the feeling that anyone had the time to think two years ahead, let alone ten or a hundred. Everyone seemed to be passing through. It was undeniably lively, but the downside was that it seemed selfish, irresponsible and randomly dangerous. I came to think of this as "The Short Now", and this suggested the possibility of its opposite - "The Long Now".

"Now" is never just a moment. The Long Now is the recognition that the precise moment you're in grows out of the past and is a seed for the future. The longer your sense of Now, the more past and future it includes. It's ironic that, at a time when humankind is at a peak of its technical powers, able to create huge global changes that will echo down the centuries, most of our social systems seem geared to increasingly short nows. Huge industries feel pressure to plan for the bottom line and the next shareholders meeting. Politicians feel forced to perform for the next election or opinion poll. The media attract bigger audiences by spurring instant and heated reactions to human interest stories while overlooking longer-term issues - the real human interest.

Meanwhile, we struggle to negotiate our way through an atmosphere of Utopian promises and dystopian threats, a minefield studded with pots of treasure. We face a future where almost anything could happen. Will we be crippled by global warming, weapons proliferation and species depletion, or liberated by space travel, world government and molecule-sized computers? We don't even want to start thinking about it. This is our peculiar form of selfishness, a studied disregard of the future. Our astonishing success as a technical civilisation has led us to complacency, to expect that things will probably just keep getting better.

But there is no reason to believe this. We might be living in the last gilded bubble of a great civilisation about to collapse into a new Dark Age, which, given our hugely amplified and widespread destructive powers, could be very dark indeed.

If we want to contribute to some sort of tenable future, we have to reach a frame of mind where it comes to