Mustard Seed and Leaven
31 He set another parable before them, saying, “The Kingdom of Heaven is like a grain of mustard seed which a man took, and sowed in his field, 32 which indeed is smaller than all seeds. But when it is grown, it is greater than the herbs and becomes a tree, so that the birds of the air come and lodge in its branches.” 33 He spoke another parable to them. “The Kingdom of Heaven is like yeast which a woman took and hid in three measures of meal, until it was all leavened.” 34 Jesus spoke all these things in parables to the multitudes; and without a parable, he didn’t speak to them, 35 that it might be fulfilled which was spoken through the prophet, saying, “I will open my mouth in parables; I will utter things hidden from the foundation of the world.”
Two pictures of small beginnings — one growing outward and visible, one working inward and unseen.
31 He set another parable before them, saying, “The Kingdom of Heaven is like a grain of mustard seed which a man took, and sowed in his field, 32 which indeed is smaller than all seeds. But when it is grown, it is greater than the herbs and becomes a tree, so that the birds of the air come and lodge in its branches.”
The mustard seed is in the earlier account Mark 4:26–41, and the contrast it draws is between a beginning small enough to lose between finger and thumb and an end large enough for birds to nest in. Set beside the previous two parables it answers a different worry: not why the field is mixed, but whether anything so unimpressive can come to much. Twelve men in a boat is the beginning being described.
The phrase smaller than all seeds is spoken as a proverb, and it was one — the mustard seed was the standard figure for the smallest thing a farmer handled, the way a hair's breadth is a standard figure for a narrow margin. The parable is not filing a botanical claim; it is using an expression its hearers used.
He spoke another parable to them. “The Kingdom of Heaven is like yeast which a woman took and hid in three measures of meal, until it was all leavened.”
The leaven is Matthew's, and it is the mustard seed's opposite number in every particular. The mustard is a man in a field; the leaven is a woman in a kitchen. The mustard grows upward where anyone can see it; the leaven is hid, and nothing visible happens for a long time. The mustard ends as a place for birds; the leaven ends by disappearing into what it changed.
The two together say that the kingdom advances in both ways, and that neither measurement is the whole account. A movement can be counted from outside; the other kind of growth cannot be counted at all, which is why it is so often assumed to have stopped.
Leaven usually stands for corruption in Scripture — the Passover swept it out Exodus 12:15, and this Gospel will use it that way within three chapters Matthew 16:6. Here it does not. What the image actually carries is a small agent transforming a whole mass from within, and the direction of that change is set by the parable, not by the ingredient. Three measures of meal is a large baking, enough bread for a crowd; the point is the ratio.
Jesus spoke all these things in parables to the multitudes; and without a parable, he didn't speak to them Matthew 13:34. The shift begun at the boat is now total, and Matthew reads it as a fulfillment rather than a retreat: "I will open my mouth in parables; I will utter things hidden from the foundation of the world" Matthew 13:35 Psalms 78:2.
The psalm quoted is a long recital of Israel's history told so a later generation would not repeat it, and its opening line calls that telling a parable. What is claimed here is not obscurity but disclosure — things kept since the world was founded, being said out loud at last, in the only form a hardened audience could still receive.
settled What this mark means