I, of course, used a time machine to "get the idea" of Unseen University from Hogwarts; I don't know what Paul [Kidby, the illustrator] used in this case. Obviously he must have used something.Simply defined, a fan thinks a trope, plot, or line was invented by a show he or she watches, when in truth its origins lie farther back in history. Tropes tend to be much older than they appear, even if they aren't one of The Oldest Ones in the Book, so it's increasingly likely that a viewer of a specific program won't be familiar with the original source of whatever is on display. This can also be inverted by fans, who see a modern adaptation of some older classic they're unfamiliar with, and incorrectly assume some newly introduced trope was part of the original work. The ultimate expression of this is the Unbuilt Trope — someone did it previously, examined it, deconstructed it, zig-zagged it, all spectacularly, finished the story's run, but is now remembered mostly nostalgically, not for its trope. See also the more extreme Fleeting Demographic Rule. Compare with classical music Covered Up, Name's the Same, Pop Cultural Osmosis, Seinfeld Is Unfunny, Revival By Commercialization, Sequel Displacement, and the Weird Al Effect. Somewhat related to Adaptation Displacement. Contrast with Newer Than They Think. Do not confuse with Older than They Look. There will be a short quiz at the end of class. For examples of people referencing this trope in fiction, see It's Been Done. See also Fan Myopia for the same effect when it's over work knowledge rather than time knowledge.