Luke’s source for this parable is ‘Q’. The comparison in the parable is between the leaven and the Kingdom. A little leaven has the power to ferment and permeate a basinful of dough. Similarly, the Kingdom of God too, though small and hidden (Lk 13: 21), will inevitably leaven the whole of human history. Just as leaven is very active and dynamic in the dough, so is the Kingdom in the world.
God’s power is dynamically operative in Jesus in the midst of human history. His power will certainly have its effects.
This pair of parables (Lk 13: 18-21) which emphasises the certainty of the growth of the Kingdom and the influence it is bound to have concludes the first part of the travel narrative of Luke (Lk 9: 51 – 13: 21).