Matthew 13 contains seven parables about the Kingdom of God/Heaven. A parable is a teaching method commonly used by rabbi's. It usually consists of taking a common task/object/event and using it to illustrate a spiritual truth. And as evidenced by the disciples, and Jesus' own explanation, they were not lessons easily grasped. Lucky for us, Matthew includes Jesus own explanation of two parables - the seeds and the weeds.
An observation: Jesus was a brilliant rabbi - his parables were memorable, yet difficult to grasp. It seemed that the wrestling with the parable was more valuable then "getting" the parable. If it was too easy to grasp. it was too easy to forget. And truth is not something discerned lightly or frivously. And Jesus is not always easy to understand. So take heart - if you read the Gospels, but find yourself mystified at some of Jesus' behavior/teachings, you are in good company.
The truth that Jesus was teaching through the parables concerned the Kingdom of Heaven/God. His first sermon in Mat 4 was "Repent, for the kingdom of heaven is at hand." The Kingdom of Heaven/God is Jesus' way of encapsulating many invigorating, scandolous, beautiful ideas into one potent phrase. God's Kingdom is a way to talk about the extent of God's rule. God's rule results in shalom/peace/rightness/justice/hesed (loyal love).
Jesus is referred to in Matthew as "Immanuel", God with us...which matches Jesus' sermon - the Kingdom of God is now Immanuel. Jesus' own name - Yeshua/Joshua means "God saves", which is another result of God's Kingdom amongst us. Of course to be outside of God's KIngdom means you are a citizen of a different kingdom. That kingdom is characterized by darkness, evil, fear, brokeness, blindness, deafness, crippledness, disasedness, etc. When Jesus healed, he was saving - his physical action reflected that person's entrance into the Kingdom of God.
Take time to wrestle with what the parables teach about the kingdom of heaven. Like most of Jesus' teaching, there is an initial grasping...but he is a brilliant teacher who provides layers and layers of understanding, which lead you up to a beautiful understanding of truth.
In a nutshell Jesus is proclaiming: trust me, you really want God's delightful, terrible, beautiful, dreadful, generous rule to envelope your existence.
He's asking you today: do you trust me?