Jesus is making a change of focus that results from a judicial act of judgment against Israel. They have refused to listen and respond to His calls for and invitations to salvation. Now, He is acting on God's warnings that though they see, they would not see truly, and though they hear, they would not understand. The understanding of the parables is limited to those who believe...at this point, the disciples. The point of this parable revolves around the seed (gospel message) and the hearer's hearts (soil). The sower is not Jesus, in this case. Rather, it is anyone who is sowing (preaching) the gospel message. The quality of the preaching is not at issue here. Rather, it is the condition of the hearts of those who hear.