Jesus preaches about the kingdom and illustrates it with parables. Two such parables appear here. What is the kingdom's character? What does it look like? The mustard seed and the leaven help us to grasp how the kingdom operates.
The general Jewish expectation was that the messianic kingdom would be established suddenly and decisively. So the surprise in these parables is the almost subtle initial form that the kingdom takes. Both mustard seed and yeast are very small in the beginning but produce something much larger. The kingdom as described in the parables is a presence that begins almost invisibly yet eventually comes to dominate.
It is perhaps fitting the parables are set here after the account of how a woman under the grip of Satan was healed. Once again Luke associates Jesus' healing activity with a picture of the powerful presence of the kingdom. One illustrates the other.
Most of Jesus' parables have a surprise, a twist, that helps to explain their point. The parable of the mustard seed is no exception. The mustard seed's growing to become a tree is surprising, almost unnatural. Here is supernatural, creative growth. Some readers miss the surprise (or complain that the image's unusual nature shows it does not come from Jesus); but the entertaining and instructive "twist" in many of Jesus' parables is a characteristic device that helps to unlock his teaching. The type of tree Jesus is envisioning here is debated. Is it the twenty-five foot Salvadora persica or the ten-foot Sinipis negra? If the latter, then he is talking about a member of the mustard family. It is not clear which is meant, though the birds in the limbs suggest Old Testament imagery (Ezek 17:22-24) of a large cedarlike tree. The point, either way, is what starts out small will end up big—big enough to make a home for many birds.
The bird imagery is significant. Three Old Testament texts have this image (Ps 104:12 and Dan 4:10-12, along with Ezekiel mentioned above). Daniel's image is interesting: the great tree of the worldly kingdom of Nebuchadnezzar is reduced to a stump by God. But the closest parallel is Ezekiel. Picturing the restoration of Davidic rule, his cedar tree sprouts from a sprig (is the sprig in turn an allusion to Is 11:1-2?). This goes in the exact reverse direction of the Nebuchadnezzar image. In this tree the birds, representing the people of the nations, will dwell in peace. In sum, the kingdom grows in surprising ways but is a place of shelter and calm for those who rest in its branches. God is restoring the work of the house of David, and all the world benefits.
The parable of the leaven is similar. Yeast slowly permeates bread dough and eventually penetrates it through and through. The woman in this parable is making a huge loaf. Three measures (Greek; NIV a large amount) of flour would probably be three seahs, or about fifty pounds. The point of this parable is not so much growth as contrast. What starts out as a pinch of yeast in a huge batch of dough ends up present throughout it. Permeation is inevitable once yeast is introduced. Implied is a growth that is slow, almost invisible, but this is not the point. Be sure of one thing, Jesus says: we may seem like a small movement, but eventually we will permeate the world.
These parables issue a call to trust the way God is developing his program. They also serve as a kind of commentary on the previous healing. Luke's reader can have hope that despite the humble beginnings of this community, the kingdom will come to have a dominating presence and will provide shelter and calm. God's plan is advancing. Opposition, whether human or spiritual, cannot stop its realization in the world. Trees built with earthly hands, like that of Nebuchadnezzar, will become stumps, but the branches of God's kingdom provide shade forever.
IVP New Testament Commentaries are made available by the generosity of InterVarsity Press.