Dear. Dr. Barber,This is a good question.
I was going over a list of parables when I notice that there are none in John. (I'm not a scholar!). I then read your article on the authorship of John. Do you think that the lack of parables says anything about the authorship? Do you know why there are no parables in John? I tried to do a search on it and couldn't find anything.
Ultimately, I have to say: I'm not sure. However, I do have some assorted thoughts on the matter that might combine together to equal some sort of answer. This is sort of "half-baked", but let me just offer a couple of ideas.
