The more civilised we become, the more we are intrigued to show that we could manage with our bare hands and brains

After a fortnight living in a tent by the sea, I am more than ever intrigued by my perennial appetite for messing about, and for making do.

It's not that I despise grand holidays in tropical paradises. It's more that I am struck by the way the essentials of a holiday draw on the same deep needs which fed our religious discussion of Paradise, feed our modern version of the love of wilderness, and led to the "castaway novel". We wonder what a perfect life would be, and how we would manage in the face of a nightmare collapse of life as we know it.

The big difference between the Victorian boys' adventure, Coral Island (by R M Ballantyne), and the adult adventure of Daniel Defoe's Robinson Crusoe is that, while the boy castaways love their atoll and find it beautiful, Crusoe hates his island. The boys are having an adventure in paradise and for Ralph, the storyteller, being a castaway is just an unfortunate consequence of following his father's seafaring vocation. Crusoe is surviving in purgatory, and sees his exile as divine punishment for disobeying his father's injunction to be satisfied with a settled life at home.

Actually, Crusoe seems very confused. Though his island is wooded and gives him a good living, he often calls it "barren" and, more understandably, "desolate". Only when he finds God, and Man Friday, does Crusoe believe his island might be "happy".

It is easy to forget the solemnity of Robinson Crusoe: here was a man who lived in a permanent state of fear for 28 years, during which his days were divided between making farms and fortifications.

But what one remembers is the immense freedom he had, even if he could not enjoy it as we fantasise we would. I don't think about Crusoe's endless toil and terror. I think about his scavenging and ingenuity. He lived, one pretends, in a state which 1960s anthropologists romantically called Original Affluence, as they misdescribed the luxuries of primitive life.

I cannot be beside the sea without beachcombing. The improbability of finding anything valuable never blunts the prospect. A decent piece of cord. A plastic device of unknown utility, to hang round my neck on the former. These are not great treasures, but I prefer finding them to twiddling a paper umbrella in a funny-coloured drink, in a bar named Castaways, in a coral-fringed resort.

Of course, Crusoe pursued a rather high-class form of beachcombing. He plundered whole ships, and reminds one of the ecstasy of thievery which makes coastal-wreckers in Cornwall into folk heroes. Our pleasure in wrecking, like a crowd's delight in looting, is that it represents a sudden, half-legitimised, carnival- style redistribution of wealth. It is the perfect example of the "something for nothing" excitement which takes people to jumble sales and scrap-yards.

We love the inventiveness of a Crusoe or a Ralph, especially in raft- making. Now, when kids don't have much chance to mess about in woods, bomb-sites, derelict factories (as post-war-boom babies could), it's lucky that grown-ups organise raft-building contests, as the sailing club at Solva (near St David's in Wales) does every summer. We entered two teams of four this month, and built a pretty competent raft in short order. We sort of proved that we could manage if the chips were down.

The more civilised we become, the more we are intrigued to show that we could manage with our bare hands and brains. We wonder whether we have gained much in all our getting and spending, when making-do is more attractive, and perhaps - one day - even necessary.

Coral Island and Robinson Crusoe don't capture the imagination because they are happy fantasies. They enthrall us because they invite us to wonder whether we could live simply, as monks and savages must.