What's in a photo?

Andreas Gursky's Rhein II, above, sold for $4,338,500 at Christie's Auction House last week to an anonymous buyer. Which leaves we mere mortals to ponder what makes it so special:

The Rhine is "one of the most symbolic motifs in German art," says Francis Outred, head of Europe in post-war and contemporary art at Christie's. It runs through Gursky's hometown of Dusseldorf, as well as six European countries, and has inspired art for centuries. But Outred contends that this photo is exceptional: "One of the most powerful and profound depictions ever to be created of the Rhine, the photo's unique scale draws an ineffable link to the actual natural landscape, inviting the viewer to cross over into its vivid picture plane."

I'll ponder on, thanks.