A glance at today's first reading shows us that we compare the kingdom to the growth of a tree. Ezekiel provides an obvious background to the Gospel 'mustard seed'.
The parable of the mustard seed stresses the great growth of the kingdom from small beginnings. From a very small seed, though not the tiniest, we can get a plant twelve feet high. The image of branches providing room for the nesting and shelter of birds occurs not only in our first reading, but also in Ezek. 31:3-9, and Dan. 4:10-22. The kingdom will receive Gentiles as well as Israelites. God's salvation has become available to all men and women.
The verses which conclude today's Gospel state clearly that the parables do not contain the complete explanation of the mystery (God's saving plan for men). The disciples of Jesus were to hear privately that the fulfillment of messianic promise had already begun in the life-work of Jesus.
This also refers to the action of grace in us. God silently works a transformation in each one of us causing us to make resolutions which shape our soul. Even though we must make the decision to become a follower of Christ, it is the Holy Spirit who, working within us, gives a supernatural tone to our thoughts, desires and actions. Yes, like the mustard seed we must grown.
Lord, let me be transformed by Your Word.