From part three of Errol Morris' investigation into Dutch forger Han Van Meegeren, here's art historian Jonathan Lopez:
Forgery is about the way the present looks at the past. The best forgeries may imitate the style of a long dead artist, but to appeal to people at the moment that they're being tricked, forgeries must also incorporate some of the aesthetic prejudices of the moment. When fakes work well, they give us a vision of the past that seems hauntingly up to date. And that's one of the things that makes forgery so seductive.