One morning in Mesopotamia, a handful of centuries before Jesus was born, man woke up and discovered he hadn't eaten all of last night's dinner. He discovered leftovers.

So was born the agricultural surplus. A man could sow, grow and harvest in a year more than the man himself could eat. It became possible to free some men from work in the fields, so that they could do other things. And it became possible to stockpile the surplus, a hedge against disaster, a stockpile that could be drawn upon should the surplus temporarily falter.

Stockpiling required two things. It required structures, built things, silos, in which to store the stockpile and protect it from rot and vermin. And it required a place to put those silos.

A place that made sense. A place that could be defended.

And where, like ancient skyscrapers, silos on the Mesopotamian plain grew, also grew cities. Like Uruk, where after the silos came artisans, teachers, merchants, laborers and bureaucrats. Those individuals, freed from the fields by the surplus but intimately connected with, and essential for, its maintenance. And there came another thing.

There came a wall.

To protect itself, to protect the silos and the surplus, Uruk erected a wall. A bright line that delineated that which was within Uruk and that which was without. A bright line between the urban and the rural. City inside, land outside.

That bright-line delineation between the rural and the urban became how we recognized city from countryside. Sometimes the wall came as a moat, as in the Seine's bifurcated flows around the Ile de la Cite. Or an anti-wall, as in the city-states of Italy, each perched on a hill over the agricultural valley below. But no matter the physical form, one knew when one passed from country to city.

Because you felt it.

The emperor's new walls

Only a few of our modern American cities have physical walls. Manhattan has its bifurcated river wall. San Francisco has its peninsula. But, by and large, the need for physical protection was something only a handful of early frontier cities needed, and those that had them, like Fort Wayne and Detroit, have lost them.

Only New Orleans still maintains its city walls for protection. Just not very well.

But although you generally can't see them, the walls still exist around every city in the nation. Depicted on maps as municipal boundaries, they let one know within from without.

Within, one can luxuriate in the city's bounty. Without, one can escape its squalor. City inside, land outside.

There is no free lunch. The urban is not the repository of all virtue, nor the rural that of all vice. Or the other way around. The city's walls protected against outside invaders, allowing culture and commerce to flourish inside. But they also kept its iniquities contained, so that the land outside would remain unspoiled, pastoral and sylvan.

Bloomington's wall, breached

Bloomington has its wall, though nothing more than a line on a map. Within, property values and taxes are both higher than without. Within, one can vote for the city's mayor, its council, even its clerk. One inch without, one cannot.

Within are available parks, public transit, trash removal, a highly professional and regular police force. Arts districts. Running water. Sanitary sewers.

Without is the countryside, where those willing to give up urban amenities are compensated, at least the theory goes, with quiet nights, with space to breathe, with room to grow. Room to grow the surplus.

There are those who have no need for the wall, for whom the bright line between the urban and the rural isn't a border to be respected. But instead, like foreign currency arbitrage, a border of opportunity.

By pretending that through the wall can be found a free lunch, a win/win Shangri-la called suburbia, containing all of the virtues of the rural, and all of the virtues of the urban, while holding none of either's vices.

Buy low, sell high, goes the developer's mantra. And what better way to do so than to buy cheap rural land, only to flip it with all the amenities of the city? And how to do that? By getting the city to breach its own walls.

Last week the city of Bloomington's Utility Services Board voted to do what city utilities, since the Los Angeles of Chinatown, have always done: not so much provide municipal water service as much as to increase the value of suburban lands, outside the city walls, for the pecuniary benefit of the land speculators who sit on their boards and hound their every meeting.

For the board voted, as they had in the past, to extend Bloomington's city sewer system beyond the wall, beyond the city and into the countryside. Once there, the sewer would enable the strip malls, the McMansions and the cul-de-sacs where those who understand the wall's purpose have always said they should never be.

With no bright line between the city and the country, how do we know where to harvest the surplus, and where to protect it?

Perhaps it doesn't matter. Perhaps in the future the farmer will simply divine where the artisan works, and the artisan will innately know within which gated community the food is grown.

Perhaps even the lines on the maps, and the communities they describe, won't matter, anymore. That appears to be the vision.

Gregory Travis can be reached at greg@littlebear.com.