To consider your analogy a bit further: Imagine you had access to only... five 18th century novels, that's it, no other knowledge about the period, the people o

To consider your analogy a bit further: Imagine you had access to only... five 18th century novels, that's it, no other knowledge about the period, the people or anything. Then you try to write your own. You can make up your own stories that are a merging of various parts of those five novels, but they'll always only contain what's in those, or some combination. If all the books deal with France then Germans or English will never make an appearance because it's literally impossible to guess that they exist since they're not in the original books (the books here are training data if that's not obvious).