Artists have been depicting the naked body for quite some time . As the Metropolitan Museum of Art puts it, this is perfectly natural, given the fact that humans spend a lot of their time without clothes, "from birth to the bath to the boudoir ." Yet, after centuries of ogling the nude body on canvas or as sculpture, audiences still have a hard time talking about what they're seeing.

Last week, when Amedeo Modigliani's "Reclining Nude" sold for a jaw-dropping $170 million at auction, Bloomberg News opted to censor the painting when it displayed the art on air. All right, we've already taken issue with the arbitrary censorship of art on TV. But what about the two anchor's responses to the work? "Too racy!" they exclaimed in unison.

Sure, Modigliani's painting depicts both the breasts and pubic hair of a naked woman, but does that mean it's racy? Nude art hangs in the halls of just about every major museum, and graces the auction block of historic institutions like Christie's and Sotheby's regularly. It's a definitive part of our creative culture -- from the Venus of Willendorf to ukioy-e to modern works by Gustav Klimt or Picasso. Can we figure out a thoughtful way of talking about it, without resorting to phrases like "racy"?

This month, Sotheby's is hosting an exhibition in its London S|2 space , titled "The Nude in the XX and XXI Century." Let's take this opportunity to not only preview a glimpse of 200 years' worth of beautiful art, but also to outline a guide to reading and understanding the naked figure in art history.