I've even heard some people create entire theological systems out of a single parable. Parables cannot be classified, categorized, and labeled for easy reference. We can try, but we're only fooling ourselves. When we classify parables, we are like children who run around trying to catch the wind in a glass jar. Yes, there's some air in there, but most of it is still outside.
Parables are elusive, enigmatic, and dangerously ambiguous.
Yes, parables are dangerous. That's why we try to domesticate them. It's like all those movies where scientists discover an alien, then kill it and dissect it so they can bury their fear with the shovel of understanding. Although Jesus is just sitting in a fishing boat today, we could easily picture him in a warship. There he sits, launching his amphibious Trojan Horses into that unsuspecting crowd on the beach.