Setting and Overview
After the parable of the sower, Matthew presents six more parables of Jesus in chapter 13, with one set of three presented to the crowd, and the second set of three presented to his disciples. The first set of three are likely still presented from the boat but stand apart from the preceding one. Unlike the parable of the sower, Jesus begins each one with a clear statement of their subject, “The kingdom of heaven is like…” What follows however, is far less clear as Jesus then describes the kingdom in ways that few would have expected.

Exposition
In the first parable of the set, Jesus compares the kingdom of heaven to a landowner who has sowed good seed but then had an enemy sow darnel, a poisonous weed, alongside the wheat. When they all grew together, this presented an issue for the landowner. If they were harvested together, the darnel could get mixed with the wheat and ruin the crop, but if the darnel was pulled out early, then because they were hard to distinguish and their roots often got tangled, then the wheat would likely get pulled up as well. For that reason, when the servants suggest pulling the darnel up, the landowner turns down their suggestion and instead says that the reapers will pull and burn the darnel at harvest time and afterwards gather the wheat. In the second parable, Jesus compares the kingdom to a mustard seed, which was the smallest seed used in agriculture in that region but which grew into a large plant or small tree. Furthermore, he states that wild birds would come and nest in its branches, which was possible, but less commonly associated with mustard plants than with larger trees (Daniel 4:12, Ezekiel 31:6.) In the third parable, Jesus compares the kingdom to leaven, which would be part of an earlier batch of dough which was set aside and then stored so that it could be mixed in with new dough and then cause the whole batch to rise. This was a process well familiar to all households of the time, and the spreading effect of the leaven made it a powerful illustration (Exodus 12, I Corinthians 5:6-8.) The amount of flour is a large amount, perhaps seen as the amount needed for a royal banquet (Genesis 18:6.)
Just as the parable of the wheat and darnel is very different from the parable of the sower, so too is its explanation. This time, Jesus first begins by identifying many elements in the parable as deliberate symbols: the owner as the Son of Man, the field as the world, the good seed as the people of the kingdom, the darnel as the people of the evil one, the enemy as Satan, the harvest as the end of the age, and the reapers as angels. The servants are not identified and apparently aren’t meant to be a specific symbol. When he then gets into the events, however, he skips over earlier events and goes to the end, which is his focus. He isn’t telling us everything about the kingdom, but rather than just correcting one important but misunderstood item. Although the people of the evil one are not yet destroyed and the people of the kingdom do still have to exist in the midst of evil and injustice, the people of the evil one are eventually destroyed (Zephaniah 1:3) and the righteous ones will shine forever (Daniel 12:3, Matthew 5:14-16, II Corinthians 3:18.)
While the parables of the mustard seed and leaven are not explicitly interpreted in the Gospel, they do offer strong clues that should allow us to see the main points. The significance of the mustard seed is that it was very small, and yet grew a large plant. The significance of the leaven is that a small amount of it could cause a large amount of dough to rise. In both cases, the small, arguably dismissible, beginning hides their power. This helps us see that the kingdom starts in a way that is far smaller than would have been imagined, but then grows significantly, transforms intensively, and becomes everything that it was promised to be (Ezekiel 17:22-24.)

Examination and Application
Jesus’ exhortation at the end of verse 43 should remind us that these are critical to not only understand, but also to respond. While the exhortation is not given in the verses, we can see how many previous exhortations in the Gospel would tie into these verses. A mustard tree might be large compared to its seed, and may be able to accomplish everything that a larger tree would, but it does not convey the majesty of a cedar. So too must we be aware as subjects of the kingdom that faithfulness to God’s commands will not often lead to worldly praise or honor (Matthew 5:11-12.) As leaven infects the whole loaf, so too are we called to “infect” the world by being salt to a decaying society (Matthew 5:13.) Finally, although we may not yet be the light that we will one day be, even now we do at least partially reflect God’s glory (II Corinthians 3:18) and so we are called to shine as lights to the world (Matthew 5:14-16.)