The video: Danish subway riders were treated to a decidedly highbrow surprise last month when members of the Copenhagen Philharmonic Orchestra serenaded them with a flash mob performance of Edvard Grieg's "Peer Gynt" on a morning train. (Watch the video below.) The collaboration between the Philharmonic and the classical music radio station Radio Klassisk was essentially a super-cultured version of a typical flash mob, in which a group assembles for a seemingly impromptu public art performance — be it a Michael Jackson dance, wedding proposal, or massive pillow fight. In this case, a lone flautist kicked things off, and eventually was joined by dozens of members of the orchestra for a rich, rousing performance that had commuters grinning with delight.

The reaction: "It's rare for a commute to be punctured by anything besides frustration," says Amanda Erickson at The Atlantic Cities. And that makes these folks the luckiest straphangers ever. And this isn't just the classiest flash mob I've ever seen, says Eyder Peralta at NPR. It's also a technical accomplishment to achieve such a pristine sound on a crowded, moving train. But "let there be no mistake," says Neetzan Zimmerman at Gawker. "As soon as this video ended, flash mobs went right back to being the worst." Have a listen: