NOTES for Mat 13:31-35
Of course, it is not quite right to pull these two parables about the Kingdom of Heaven out of the whole set of parables. Scripture's ways of describing the Kingdom are varied. But let us imagine something like both this mustard seed and this leaven. It is something very small, yet capable of growth (other parables speak of this through their own images), growth that cannot be compared with its original size. This growth can take place both through inner change and development (seed-tree) and through influence on what surrounds it (leaven-dough), but in one way or another the original quality disappears, being transformed into something new that benefits someone else (the birds of the air, the housewife). Interesting, is it not?