We had these parables two Sundays ago. Let me repeat my remarks from then.
Jesus, while growing up with Joseph and Mary, had been fascinated with the changes that time brings about with seeds and grains.
Then, later as an adult, he became aware of the many ways that the lives of people underwent similar changes. Today he gives us two parables that grew out of the similarities he'd seen.
As a child he might have marveled over how a mustard seed while being smaller than all other seeds, at full growth could be alive with yellow flowers. And he could have been struck by a similar change that took place when one kind word from his mother put Nazareth’s biggest crab to humming a sweet song.
Watching his mother kneed bread dough, and watching her put lumps of it into their pans, he might have asked why she didn’t fill the pans. And after she told him to wait to see what the yeast would do, he did wait, and he was delighted to see tanned inches of the dough pushing over the sides and ends of their pans.
Christians with urges to lead full religious lives in convents or monasteries could do well to listen to what Jesus was telling them with his parable of the yeast. It is better for these people to be like yeast, mixing fully with ordinary people, raising them up with kindness and truth.