Being sure about the provenance of a work of art isn’t such an easy matter, as the recent Nazi stolen art lists have shown. When did we start to care about the history of a painting? “I think it entered the written history of art probably at the time that people started collecting art as something that one appreciates rather than something one has for its function. It’s really when there was a shift over from stuff that you accumulated because it was a part of your life, religious devotion or practice to things you appreciated for their own sake. And that, I guess, happened about 1500.” – Chicago Tribune