In considering the parables of Jesus, there are a few contextual concepts we need to understand about Jesus’ presentations in Matthew’s Gospel.
First, after Jesus was rejected in Matthew 12 He spoke in public often using parables. His purpose in doing so was stated plainly in 13:11-17. He was taking away from those who had rejected Him the opportunity to learn any further of what His ministry was really about. Those who had faith in Him would be provided more information. In simple terms, Jesus spoke publicly in parables to veil the truth from those who had rejected Him. He often spoke to His disciples afterward to explain His intended meaning (as in Mt 13:36-43), and sometimes spoke directly to those disciples using parables for a different reason altogether.
Second, Jesus’ teaching on the kingdom was straightforward. There was only one kingdom – God’s eternal spiritual kingdom, located presently in the heavens (hence the oft repeated phrase in Matthew, “the kingdom of the heavens”). Because of covenants God had made earlier (Abrahamic and Davidic), that heavenly, spiritual kingdom would one day come to earth in a physical manifestation, with the Messiah (the God-man) as the King. So there would not be two kingdoms, with one spiritual and the other physical. There was simply one kingdom that would change locations in fulfillment of God’s promises.
Third, because Jesus intended to obscure and not make things plain when He spoke publicly in parables, we have to exercise caution when trying to interpret them. The easiest mistake to make is to think that every aspect of the parable is symbolic of some important reality. Let’s spend a moment thinking about the components of metaphor, because that is really all a parable is.
A metaphor has two basic parts, (1) the tenor, which is the original subject, and (2) the vehicle, which is the reimagining of the original subject. Oftentimes the tenor and the vehicle are connected by a verb. For example, when saying someone is a gem, of course we are not intending to communicate that the person is literally a rock of some pecuniary value. What we are saying is that someone (tenor) is (connecting verb) a person of high quality and value (gem as the illustrating vehicle). Just as in most commonly used metaphors, a parable is used to communicate a single basic truth. There aren’t typically hidden or deeper meanings beyond the basic “vehicle” that illustrates the reality.
In Matthew 13:31-32, for example, Jesus speaks to His disciples a parable. The audience in this case is not unbelievers, but believers (primarily, anyway). So Jesus’ purpose in this parable is not to veil (as it was in 13:3-9), but to illustrate. There is no explanation given in the text, so the natural interpretation would be to understand that Jesus is illustrating a single basic point. “The kingdom of the heavens is like a mustard seed.” Here is a classic tenor and vehicle. The kingdom of the heavens is the reality, the mustard seed is the illustration. How is Jesus comparing the kingdom of the heavens to a mustard seed? The mustard seed is tiny, but when it grows it becomes a large tree – large enough for birds to nest in its branches. The illustration is simply that the kingdom starts small and then becomes large. There is no necessary significance – nor any that can be inferred naturally from the passage – of the man who sowed the seed, nor of the birds who nest in the tree’s branches. Those elements are tertiary, simply helping to round out the illustration of the kingdom as something that starts small and ends really big.
Because the reference to birds of the air nesting in branches appears elsewhere, some suggest this parable is connected to those references, but there is no necessary or natural connection. Ezekiel 17:22-24, for example, speaks of a cedar twig that becomes a grand tree, and birds of every kind will nest under it and enjoy its shade. Note also the that God says that “all the trees of the field will know…” Once again, tenor and vehicle. Trees are personified here, or at least attributed anthropomorphic qualities. The trees are not just trees in Ezekiel 17:24. They are metaphorical references. But the tree in Matthew 13:31-32 is identified as the kingdom of the heavens, and the birds are not identified in any detail (not “of every kind” as in Ezek 17:23), so while we might want to draw a theological connection, there is no textual reason to do so, thus it is safer not to assume a theological connection, and simply let the straightforward metaphor (of the kingdom as being like the small seed that grows into a huge tree) stand on its own.
In short, when we examine the parables of Jesus, we can typically identify one primary principle characteristic of the tenor (original subject) illustrated by the vehicle in order to obscure the meaning (as in the case of Jesus’ post-rejection public parables) or to convey a very simple principle to Jesus’ disciples. Consequently, the parables of Jesus are much simpler to handle than we often give them credit for. In the case of Jesus’ parables, digging for hidden meanings can put us in the same predicament as expecting hidden meanings in other kinds of Biblical literature – we can lose the simple, natural, intended meaning of the Author.