there are only so many combinations of words, punctuation, and spacing. only so many letters in the alphabet. so the set of things that can possibly be written is finite. it is like our physical earth. there are only so many possible combinations of DNA. a presumably finite number of elements present on earth, combined in different ways. the only difference is that they are already all rendered and out there and the difficulty for an explorer is to go and find them. whereas the difficulty for a writer is that some writings, while possible, have not yet been written.