They had been denying wishful reports of a reunion since the day they parted more than a decade ago, but on a cool breezy evening on the sprawling Great Lawn of Manhattan's Central Park, Paul Simon and Art Garfunkel, both 39, staged a concert together for the first time in 11 years. In a free, two-hour program, they offered the delicate but enduring classics that turned their Queens junior high friendship into one of the most influential and lucrative pop music acts of all time.

The crowd, the largest ever in the park—possibly the largest to assemble anywhere for a single act—was estimated at 500,000, ranging from teens in denim and down to 40ish folkies. Yet even those on the perimeter, hundreds of yards from the stage, were palpably moved by the peerless harmonies and melodies of The Boxer, Mrs. Robinson, Homeward Bound, Scarborough Fair and 16 other songs. For the principals, however, the crash rehearsals of song arrangements dating back to the early '60s reportedly made the reunion seem, well, crazy after all these years. Any tension around S&G was understandable. "They took a terrible risk," says one Simon associate. "They could have not agreed on anything. Everybody sort of felt at one point or another, 'God, I wish they'd never done this.' It was like going on vacation with your ex-wife."

After they split in 1970 to pursue separate interests, Garfunkel tried films (Catch-22, Carnal Knowledge, Bad Timing). Simon created some of his finest music on There Goes Rhymin' Simon and Still Crazy A Her All These Years, appeared briefly in Annie Hall, then scripted and starred in his One-Trick Pony last year. They did team up to record the single My Little Town in 1975 and also appeared together on Saturday Night Live that year. This year Simon joined Garfunkel on one song from his album Scissors Cut. What got them together again was neither money nor love but jeans tycoon Warren Hirsh's effort to raise funds to restore the Great Lawn. (James Taylor and Elton John had performed there in previous years.) All revenues from the concert—some $100,000 in T-shirt and memorabilia sales—went to the Parks Department, and the cleanup of the grounds was donated by the promoters.

If the concert proved anything beyond the fact that a half million New Yorkers can congregate peacefully, it was that the whole of a Simon and Garfunkel concert is greater than the sum of its parts. The show was videoed and recorded for a TV special and a possible album, but as for a more permanent coupling, the chances sadly seemed to go slip-slidin' away with the late evening light. "This was a onetime get-together," says Simon's personal manager, Ian Hoblyn. "Still, they saw that crowd, and somewhere in the recesses, though not consciously, they must have felt, 'Hey, look what we could do.' "