He told them another parable: The kingdom of heaven is like a mustard seed, which a man took and planted in his field. Though it is the smallest of all seeds, yet when it grows, it is the largest of garden plants and becomes a tree, so that the birds come and perch in its branches.
Though it starts small, it grows large. Though it is the greatest thing above all creation, it is fully contained within the single seed.
Consider the mustard seed. It needs no addition, just to grow. It is self contained, self replicating, and able to endure. This is what the Kingdom is like.