If a Great Writer/Artist/Musician create a great work, is the time period associated with the great work relate to the time the Great Person was borned, or the time the great work was created? For example, I get a great writer in medieval era, but I kept him idle until the renaissance era, then I use him to create great work. Does that piece of work count as medieval or renaissance great work? I was curious because sometimes you want to optimize period of great works for theming purposes.