We always tend to tame the parables. A parable is supposed to make the listener question what they have heard because parables reveal a truth full on. We tame them because we have heard them so often and we think we know what they mean.
The first parable I don't think I have ever heard explained in a sermon. It's a description of truths about what the kingdom of God is and we tend to ignore it because we can't quite get a hold on what Jesus is saying. Usually if a seed comes up we know where it's source is from, what does he mean we can't tell where it came from?
Might it just be about how there is nothing we can do to plant the kingdom?
It just springs up kinda like when we fall in love? God's love for us and what is a blessed ministry and what isn't has been rated for years. If one of our numbers fail we think the whole ministry has failed. Look at Rob Bell and all the controversy he started with his book "Love Wins". There were people who were sure he would be silenced and yet he has again been in the news for sharing that God loves homosexuals. His downfall is not as well advertised this time but it has garnered attention.
We like measurable signs of the kingdom. This person is in, this one is out. This person is a waste of time and this one is not. Categories are what we thrive on and yet Jesus is telling us we don't get to pick and choose the plant our responsibility is only to harvest. Could that mean showing our attention to the wild people we wouldn't expect God to include?
This is actually where a parable takes us, into further questions of the truth. We cannot hide out expecting everything will become clear in one sitting. God's truths are revealed slowly over time and we should be brave enough to question. How much are we challenged on faith when we dare to keep peeling back the layers of the question? The rewards are a kingdom worth a treasure.