Frida Kahlo's self-portraits made her famous around the world. But some of her lesser-known works -- her love letters to Jose Bartoli -- went up for auction in New York on Wednesday.

While the love letters are well-preserved and are considered a treasure, is it strange to have Kahlo's intimate items up for grabs? Peter Costanzo, director of the rare books, autographs and photographs department at Doyle's New York, tells more.