In this winter of our discontent, when Philadelphia's City Hall is too broke to fund parades, keep libraries open on weekends, or even scoop up curbside piles of raked leaves, you can't help longing for a little brightness during the holiday season. Just don't count on finding that old seasonal twinkle in Rittenhouse Square.

Yes, the city has pulled the plug on the annual holiday lights, those open-work globes that dangle from the trees and transform a merely beautiful urban park into something out of a Victorian storybook. The Friends of Rittenhouse Square are scrambling to replace the city's annual contribution with private donations. They have until Monday to come up with the outstanding $30,000, or the park will go without its finery this year (see www.friendsofrittenhouse.org/).

The Friends have supporters in high places, so by the time you read this the Christmas crisis of 2009 may be averted. But the fact that Philadelphia can no longer afford even this modest expense at its signature downtown park is further evidence that city government is in full retreat as the primary steward of public space.

The Friends already cover virtually all of the square's upkeep, from trash pickup to spring tulips, contributing $420,000 annually from fund-raising, according to the group's president, Wendy Rosen. The contribution toward the holiday lights was the only regular, tax-funded allocation that the city was still making in Rittenhouse Square, other than occasional big-ticket improvements like sidewalks.

Given that so many essential city services were pared in this year's budget crisis, it's probably not a good moment to argue for special treatment. Still, it's worth remembering that parks and public spaces are more than indulgences. They're essential to Philadelphia's long-term viability. That's especially true of Rittenhouse Square, which serves as the city's unofficial living room and is regularly mobbed by the full spectrum of its population.

The state of the seven-acre square matters because, as work becomes less tethered to a specific place, people and employers are increasingly choosing their home address based on the appeal of the local amenities. James Corner, the Penn professor who designed New York's wildly successful High Line park, argued at a recent panel discussion that when hard times come, cities need to ratchet up "their commitment to parks if they hope to retain talent."

But if the current arrangement barely keeps Rittenhouse Square looking trim now, what's the alternative? Should Rittenhouse Square go completely private, as Franklin Square did?

The struggle to fund the holiday lights has certainly exposed the weakness of the Friends' low-key approach. The nonprofit group has no paid staff and no formal relationship with the city. Rosen worries that it's becoming harder to keep up with the park's needs. Graffiti has returned to the elegant balustrades, designed by Paul Philippe Cret in 1913, because the Friends can't afford 24-hour security and the city police don't have the manpower.

At the same time, the Friends have little say over management decisions. The city has eagerly exploited Rittenhouse Square's money-making potential by scheduling a variety of paying events, some more commercial than others. They range from a costumed puppy parade around the fountain to an annual two-day art show. Many of these events bring in the crowds, but little money for the park.

Yet those events, about 25 a year, add to the maintenance burden. Because of the park's heavy use, there are days when it's impossible to find a tranquil corner to escape the city's bustle. Lunchtime visitors were jolted out of the afternoon calm recently when a fashion show sponsored by T.J. Maxx devolved into a pure sales event, with the MC shouting out prices like a carnival barker.

In response to the pressures, the Friends recently hired Daniel A. Biederman, a New York consultant who also happens to be president of the nonprofit corporation that runs Bryant Park. His group was the first to organize a private takeover of a public park, a model that has been widely emulated.

Such organizations can work as long as cities remain a vigilant advocate for democratic assembly. The Bryant Park group is credited with transforming the seedy, no-go enclave dubbed Needle Park into a gracious and popular green refuge that brings in $7 million a year from events, food concessions, sponsors, and assessments on the adjacent property owners. But the nonprofit recently had to evict the Fashion Week tents because the event hogged so much park time. It cost the group a third of its income.

Rosen says the Rittenhouse Square group is more likely to explore a hybrid management structure where the Friends would hire a paid director to pursue new money-making strategies, but the city would remain involved through Fairmount Park.

The Friends believe a director would do a better job of organizing events that are compatible with the square, while driving a harder bargain with sponsors to raise more money. Technically, the city is supposed to plow event fees back into the park, but Rosen would like to create "more transparency."

Striking the balance between public and private goals will be tricky. Should Rittenhouse Square allow a food concession? Franklin Square did, but it isn't surrounded by restaurants. If Rittenhouse Square goes private, it would be the third of the city's original four corners to give up on government. After Washington Square was taken by Independence National Historical Park, conditions improved greatly.

The new management structure wouldn't be just about making money. Rosen can imagine setting aside space for yoga classes or a children's story hour. She wants to close the park's 18th Street side for occasional block parties with local restaurants.

Rittenhouse Square has long ceased to be just a neighborhood park. It's a great social meeting ground for the whole city. It should remain a place where residents and visitors can go and do nothing more than sit on a bench and enjoy a beautiful day.

Contact architecture critic Inga Saffron at 215-854-2213 or isaffron@phillynews.com.