Parables of the Kingdom: ‘Like a Mustard Seed’

All three Synoptic Gospels feature this parable of Jesus—Matthew 13:31–32; Mark 4:30–32; and Luke 13:18–19—with some minor variations in the detail. It’s a very short parable and at first blush may scarcely seem worthy of an article. But there’s a whole lot more going on here than would at first appear. Spoiler alert: typical sermons usually miss the main things that the parable is pointing to!

Here’s Matthew’s version:

‘The kingdom of heaven is like a mustard seed, which a man took and planted in his field. Though it is the smallest of all seeds, yet when it grows, it is the largest of garden plants and becomes a tree, so that the birds come and perch in its branches.’

It’s easy to assume that to understand the parable, we should begin with the fact that it’s a seed and end with a ‘starts small, grows big’ kind of conclusion—job done. But for a first-century Jewish listener, familiar with Israel’s Scriptures, the key to its interpretation is embedded in the final phrase, which echoes two passages in Ezekiel: 17:22–23 and, especially, 31:3–6 (cf. Daniel 4:10–12; 20–22).

The verbal clue is, “the birds come and perch in its branches” (Matt. 13), which evokes “the birds of the sky nested in its boughs” (Ezek. 31) and “Birds of every kind will nest in it; they will find shelter in the shade of its branches” (Ezek. 17).             

Rather than featuring a mustard plant, the Ezekiel passages feature a cedar tree. The parable is inviting a ‘superficially similar, yet qualitatively different’ contrasting of the mustard plant versus the cedar tree. This will be the parable’s principal teaching point, ‘below the surface’ as it were.

(The meaning of a parable is never to be found in the surface ingredients; they are simply a ‘teaching-neutral’ vehicle for the real teaching point. For example, the parable of Lazarus, Abraham, and the unnamed rich man, is not offering a picture of what we call ‘hell’—Jesus’ teaching point is just piggy-backing on how people at the time popularly pictured ‘the place of the dead’. The parable is saying more through the rich man being unnamed, and hence forgotten in the life to come, than it ever is about hell in the life to come.)            

The mustard seed imagery in the parable is the kingdom of God. The cedar tree imagery in Ezekiel 31 is the empires of men. As Daniel Block says, “The cedar is a standard ancient Near Eastern metaphor for imperial greatness”—strong, tall, and majestic—especially the great cedars of Lebanon.

Ezekiel is deploying cedar tree imagery to prophesy against Egypt, as the proud and arrogant regional superpower of its day, warning Pharaoh of an impending fate similar to that which befell the great empire of Assyria before it. “Consider Assyria, once a cedar in Lebanon (v.3) . . . the most ruthless of foreign nations cut it down and left it” (v.12) . . . you, too, will be brought down” (v.18). A historical likening is sourced to deliver a contemporary prophetic warning.   

The shared reference to ‘birds’ is not accidental, either. The ‘birds of the air’ (nesting in its branches) was an established ancient world metaphor for dependent people from other nations coming to find shelter and protection. Tangentially, the imagery may echo the nations streaming to Jerusalem in the messianic era (e.g., Isaiah 2:2).   

When Jesus says that the mustard seed is the smallest, he’s not asserting a timeless horticultural truth (evangelical shibboleths of the inerrancy of Scripture notwithstanding). Factually, the mustard seed isn’t the smallest in the world. But Jesus’ phraseology isn’t intended to convey that. In rabbinic usage, the mustard seed was a motif or metaphor for smallness.

The imagery of a cedar tree is the one you would reach for to picture a dominating world empire. The imagery of a mustard plant is . . . not! In fact, it’s almost the complete opposite.

Once we’re aware that ‘kingdom’ versus ‘empire’ is the underlying theme of the parable, there are several features we can draw out for comparing and contrasting.

The ‘cedar tree’ empires of men are tightly controlled, elitist, and ruled ‘top down’ by a strong man emperor or dictator. The ‘mustard plant’ kingdom of God is, in contrast, a ‘disruptor’. It’s led by servants, not masters. It’s topsy-turvy: the least are the greatest. No human agency can control it; it goes wherever it wishes and does whatever it pleases. It rejects the trappings of earthly majesty and is frankly rather unmanageable in human terms. And as if to emphasise its modesty and humility, it’s technically a weed.

In worldly terms, Jesus has put forward a rather unimpressive (if not laughable) image to liken the kingdom to, compared to the far more obvious imagery of a tall, proud, and stately cedar tree that would symbolise human greatness. It’s the difference between the imagery of a Rolls-Royce limousine and Del Boy’s Reliant Robin (technically a Reliant Regal Supervan III, as Only Fools and Horses devotees will know). Each is a form of transport, and they coincidentally share the same initials, but from that point on, the parallel lines of correspondence quickly diverge (they don’t even share the same number of wheels).     

When Jesus says that the mustard plant “becomes a tree,” that’s not because it changes into a tree. It never becomes a tree, actually, and nor can it, because a tree has fundamentally different characteristics, just as ‘kingdom’ has to ‘empire’. The mustard plant of the kingdom becomes a tree functionally for the sheltering and protection of those in need, but it does so in a kingdom way (through serving and loving, as family), not in an empire way (through dominating and subjugating, as vassals); only in those senses does it ‘become a tree’. 

The empires of men (yes, it invariably is men) acquire their power and riches through taking lives and oppressing people—the kingdom of God acquires its power and riches through enhancing life and liberating people. Empires are aggressive and colonial—the kingdom is benevolent and paternal. Empires are led by coercion—the kingdom is led by consent. Empires are dictatorial, relying on the imposition of military might—the kingdom is invitational, relying on the persuasiveness of sacrificial love.

In Jesus’ kingdom motifs, such as this parable of the mustard seed, ‘greatness’ (and indeed, power) is being re-imaged and reimagined.

In choosing the mustard seed, Jesus is offering a subversive image to contrast ‘kingdom’ with ‘empire’ on several levels; and by calling the mustard plant of the kingdom ‘a tree’ he’s being mischievously hyperbolic, since everyone listening knows full well that it’s not a tree. Maybe that’s the ‘shock factor’—that unexpected ‘twist’ in the narrative that everyone listening to a parable is always on the lookout for: “Tree? In what sense is that a tree …?”   

And then, finally, as is often the case with Jesus’ parables, even the seemingly most insignificant phrase or detail should not be overlooked. The kingdom is like a mustard seed which a man took and planted in his field. But, hold on—no one would plant a mustard seed in their field. Here’s another shock! Unless, of course, they’re signalling something fundamentally different, and intentionally subversive to the status quo.  

Once you plant a mustard seed, there’s no going back. The plant grows like wildfire, and it’s a messy, odd-shaped, seemingly uncontrolled, sprawling mass.  It’s not splendid, and it’s not regal, as those terms are generally applied to the symbols of human empire. But as they say, “Once it’s planted, you’ll never get rid of it”—a phrase that’s usually intended negatively, but in this case, it’s reflecting a quality.  

Obviously, we can still benefit from the standard sermon readings of the parable. But it wasn’t the mustard seed’s smallness that caused Jesus to choose it as a kingdom motif; rather, it signified the very opposite of everything that the empire motif of a cedar tree represented.             

Photo: Magnus Manske / Wikimedia Commons / CC BY-SA 3.0