Leading article: Virtual shopping, with bags of nostalgia

Enjoy that Saturday morning supermarket experience while you can. Thrill to the hum of trolley wheels on marble veneer. Delight in the lush tropical green of the fresh fruit and veg section. Enter a trance-like state to the crazy beeping of laser barcode scanners. Congratulate yourself on checking the pence-per-gram price of detergent (do not pause to ask what detergent is for). Buy yourself a treat of Belgian chocolates, in effect free because of the loyalty points amassed today.

Supermarket shopping is the great cultural phenomenon of our age, and all of life is there. Not just the petrol station, the chemist, the newsagent, the tobacconist, the bank, the electricity payment centre, but now the dentist, the gym, the cafe, the Post Office and soon the doctor, the church, the candlestick maker and anything else you might want to leave your house for. For most people it is still a chore, but it has become quite a pleasant chore; we do meet people we know there, we are nice to children and even chat to strangers. Young men may not, pace Sainsbury's advertising, meet young women, but for many people shopping in air-conditioned neon theme parks is a social experience.

We have reached the high point of a social revolution. Time was when supermarkets were seen as a threat, an invasion of American cultural imperialism. They would close down friendly local shops and kill off town centres, make us buy things we do not need and force us to use our cars when really we would much rather walk. Much of this is still true, but we have learned to love them nevertheless.

So what does the future hold as Tesco, currently holding the upper hand, struggles with Sainsbury to keep ahead? Supermarkets as the complete invented community? No, it may be worse than they think: we may end up thinking with warm nostalgic affection of those days when we all used to congregate in the temples of materialism and bump into next-door neighbours at the fresh herbs counter. The real importance of developments in British grocery retailing is that the pace of change shows no sign of slackening: Tesco overtook Sainsbury because it continued to innovate while its rival stuck to a conservative vision of supermarketing. Which means that today's supermarket will be out of date before we know it.

Just consider what previous cycles of social change tell us. In the middle of the last century the railways were a symbol of alienation, destroying cities, cutting through unspoilt countryside and bringing noise and crowds to peaceful places. Then they became central to our national life, and generations grew up imprinted with memories of slam doors and luggage racks and wooden-roofed stations. Now the golden age is over, and trains are a staple of British nostalgia, woven into the fabric of children's fiction and immortalised in toys. To many of our car-bound infants, "train" signifies a steam engine (which they have never seen in real life) rather than an InterCity 125 or Eurostar.

Cars are undergoing a similar process. Initially they, too, were a threat, a dangerous nuisance and plaything of the rich, but even more than trains or supermarkets they have shaped our lives. Their golden age is also coming to an end, as we report today, with the Road Reduction Bill and the operation to remove Devon protesters from their bunkers. In the case of roads it is less clear how the car will eventually be replaced. But already the nostalgia is strong - not so much in the fetish for old cars but in the more prevalent dream of the open road. All car advertisements on television feature the mythical landscapes of deserted country roads or wide empty spaces.

The same cycle of hostility and hysteria, turning into enjoyment and engagement and finally declining into nostalgia, has marked all the great changes in British society. The suburb was also once a threat, spreading in ribbons across our countryside until it was tamed and then hemmed in by green belts and structure plans. Now we all live in suburbs, and the older kinds, the Thirties semis, have become one of the most desirable class of residence.

Comics, Enid Blyton books, television and now computer games - all were derided as crude and morally degraded. At the various stages of the cycle, the Dandy and Beano comics are now quaint wholesome relics. The menace of Dennis has been reincarnated in Viz, while DC Thompson's superheroes now threaten the moral fibre of the nation's youth in the form of violent computer games.

As television is about to fragment into hundreds of channels, the common past experiences of Morecambe and Wise and Dad's Army exert an ever stronger nostalgic pull. It won't be long before Sonic the Hedgehog and Earthworm Jim become endearing museum pieces. How sweet and innocent will seem the idea of children glued to such simple entertainment for hours on end.

The same will happen to supermarkets when the home shopping revolution turns them into automated packing stations for home delivery fleets. Mind you, home shopping will only really take off when it actually becomes a computer game which satisfies yearnings not fulfilled in real supermarkets. If people can drive a trolley on their home computer which has straight wheels and can barge other trolleys out of the way, then people will start to prefer virtual shopping.

Then the Lottery Heritage people will fund the Supermarket Museum, displaying artefacts like shelf labels and carrier bags. It will give children the chance to dress up as checkout staff and try the mind-rotting chore of passing barcodes across beams of red light. And have a display to trace the history of trolley design.

So maybe Sainsbury's profits warning is a signal to start revelling in a passing way of life. Have a historic Saturday morning!