Very often painters will paint within the history of painting, (or even of other Arts), and there should be some way for users to create intertextual links between paintings. this could be as simple as for example showing Gerhard Richter's series of paintings where he repaints the Annunciation of Titian, to other things like the connection between the Arnolfini Portrait and Las Meninas, and so on, and so forth...!!! Yay!