As someone who typically cuts up old postcards to make art (to the horror of some serious postcard collectors), I am bemused but reminded some things are too good to cut up by the current show at San Francisco’s Main Library. A Little Piece of Mexico - The Postcards of Guillermo Kahlo and His Contemporaries is on view in the library’s Jewett Gallery through December 29th. The exhibit features hundreds of postcards of Mexico circa 1900 by various photographers including the German-born, Mexican photographer Guillermo Kahlo – the father of Frida Kahlo. Some are displayed on black felt, Aztec-inspired pyramids in glass cases – a nice curatorial touch. I have to look a little more closely at my old postcards before I cut them up, I could have some Guillermo Kahlos in that box.