We began chapter 4 with Jesus teaching on the Kingdom of God. Because of the size of the crowds, he got into a boat, sat down and began to teach using parables as his form of communication.
Remember, a parable is a story cast alongside a spiritual truth. It is a picture that becomes a mirror that becomes a window. According to Matthew 13: 10-17, Jesus spoke in parables so that the sincere seeker would understand and the insincere seeker would remain in the dark.