Here is some theological exegesis I am thinking through, resulting from a subconscious insight. Lately I have been reading some books concerning the Jewish roots of Christianity, and other material on the role of (biblical) Israel in Christian theology, and these ideas have been pervading my thoughts, directing what I look for in how I see things: reading theology, writing, and—apparently—other subconscious activities, such as watching my wife bake zucchini bread. I was watching her, and as yeast got mentioned in our conversation, it dawned upon me: the parable of the leaven in the synoptic Gospels has something to say about Israel within it.
Another parable he spoke to them: ‘the kingdom of heaven is like leaven, which a woman took and hid in three measures of meal until it was all leavened.’ (Matt. 13:33)
It seemed me that the meal (or flour) could signify Israel waiting for leaven. The defining moment in Israel’s history (her “historical creation”) was the Exodus, in which the slaves left Egypt eating un-leavened bread. They lived a history which, ultimately, left them still living as those without the time and “political” space to depart from a way of life in which bread is no longer eaten in a hurry, with walking stick in hand and cloak over shoulders. It would seem, on this interpretation, that Israel is bread waiting for leaven; Israel was characterized by a certain incompleteness, which took the form of longing for their true Davidic king, the Messiah. To continue this reading of the parable, Jesus is the Messiah, being the leaven to be worked through the meal until it is leavened.
But then upon considering that leaven is older dough, which has had time to grow certain bacteria and to therefore activate the new dough, it seems that Israel is the leaven (or older dough). On this reading, Israel could be seen as the necessary “ingredient” to bring fermentation to Gentiles, who are currently being invited into the covenant. If one interprets this parable in conjunction with the previous parable about the mustard seed (it appears after this parable in Matthew and Luke), then the humble beginnings of Israel coming to fruition in her promised king (a common reading of the parable of the mustard seed) could play nicely into a parable in which Israel is the leaven being placed into the meal (the world), working all of the way through it. I am unsure which direction to go with this parable, but I think either way draws attention to possibilities of time, and how time might relate Israel to her awaited king (assuming the kingdom and kingship of God is what has been promised to Israel—something I am trying to keep in mind), or Israel to the nations.