Given its outsize notoriety, it's worth noting that the cloth-draped chain-link fence corralling Franklin Square for the Philadelphia Chinese Lantern Festival is not exactly the Great Wall. But it has caused great controversy for some good reasons.

For all the suddenness with which the fence separated one of William Penn's five original squares from his "greene country towne," it's the result of a gradual accumulation of private prerogatives in public parks. Historic Philadelphia Inc., the nonprofit to which the then-shabby square was turned over a decade ago, has transformed it into a delightful urban oasis partly by virtue of money-making concessions such as a burger stand, an old-fashioned carousel, and a miniature golf course bearing adorable dollhouse versions of Philadelphia monuments.

In that light, it's not impossible to understand Historic Philadelphia's decision to celebrate its decennial by allowing the for-profit lantern festival to take over the square for seven weeks. Nevertheless, if anyone was wondering where the line between tolerable and intolerable monetization of a public asset lies, it has been aptly delineated by the lantern festival's great fence.

A production of a China-based concern known as Sichuan Tianyu Cultural Transmission Co., the lantern festival convenes a host of colorful, elaborate, and, after sunset, glowing silk-and-steel constructions, ranging from pagodas and arches to flowers and animals, headlined by a giant, undulating dragon. Besides restricting the show to paying customers, the fence enhances the striking nighttime effect of the lanterns, which are accompanied by performances, food, and drinks. Though much of the park is roped off for the displays, the public may pass through until about 5 p.m. From 6 until 10 or 11 nightly, admission is a steep $17 a head ($12 for kids).

Historic Philadelphia, which also runs the Betsy Ross House and Once Upon a Nation storytelling and reenactments, expects the festival to produce $220,000 for the organization. With 9,000 attending last weekend alone, Sichuan Tianyu can be expected to gross much more.

The company has staged the festival elsewhere, including a New Orleans botanical garden and a North Carolina amphitheater, venues that typically charge admission. Franklin Square, by contrast, is a small public park on the edges of Chinatown and Old City, neighborhoods with relatively little open space. Closing it every afternoon at the height of spring, especially without more extensive public notice and input, is unlikely to be justified by the crowds and money generated. If the revenue can't be done without, Historic Philadelphia and the city need to reevaluate their arrangement and their respective budgets.

No one is naively insisting that the group can't generate revenue, which it has done to the city's benefit for a decade. But the idea that the rehabilitated park provides an important public benefit, which it does, can't be squared with the notion that dramatically reducing public access to it doesn't really matter.

The dismay with which some have greeted the fencing-in of Franklin Square is in one respect a compliment to Historic Philadelphia's efforts so far. This instance of overreach will not diminish that success as long as its lessons are learned.