This entire passage is unique to the Gospel of Matthew and is not found in any other Gospel. It can be divided into three sections: the parable, its interpretation, and the dialogue with the disciples.
Jesus Christ: His Life and Teaching, Vol.4 - The Parables of Jesus, Metropolitan Hilarion Alfeyev
Matthew 13: 47 Again, the kingdom of heaven is like unto a net, that was cast into the sea, and gathered of every kind: 48 Which, when it was full, they drew to shore, and sat down, and gathered the good into vessels, but cast the bad away.
49 So shall it be at the end of the world: the angels shall come forth, and sever the wicked from among the just, 50 And shall cast them into the furnace of fire: there shall be wailing and gnashing of teeth. 51 Jesus saith unto them, Have ye understood all these things? They say unto him, Yea, Lord.
52 Then said he unto them, Therefore every scribe which is instructed unto the kingdom of heaven is like unto a man that is an householder, which bringeth forth out of his treasure things new and old.
As noted, this passage can be divided into three parts; further, the parable itself can be divided into three parts: the process of catching fish, the process of pulling the net to shore, and the process of sorting fish.
This process was well known to many of the disciples – certainly to Peter, Andrew, James and John. Three of these four are regularly highlighted as the disciples closest to Jesus. Their calling was accompanied by a night of fruitless fishing. Not having caught a single fish, Jesus commanded them to throw their nets into the water. The nets were so full that they broke. From then on, they were to be fishers of men.
Jesus wanted to convey the essence of his good news to his disciples in the most recognizable imagery.
Just as the disciples could see themselves in the last two parables – the treasure in the field and the pearl of great price – they could see themselves in this parable. Just as the protagonists did in the previous two parables, the disciples also had given up everything to gain this most valuable treasure of following Jesus. And in this parable, the analogy to what was their daily lives helped bring the parable to life.
This parable, like the parable of the wheat and tares, concerns the idea of a final judgment – a separation of the righteous from all others. Here, the wicked will be separated from the just, and cast into a furnace of fire.
Both speak of the final reality that will conclude human life: the dread judgment.
For this parable, the disciples appear to have quickly understood the meaning, answering affirmatively to Jesus when asked. But then there is something additional that seems, at first glance, out of place. Here, we see the scribe. In almost all cases, the scribes are presented by Jesus in a negative light: “woe to you, scribes and Pharisees, hypocrites.”
Yet, in a couple of cases, the term “scribe” has a positive connotation. The first case is in this parable. The second is found later in this same gospel:
Matthew 23: 34 Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city:
So, how is this last verse to be understood, especially in connection to the parable and teaching? First, the idea of the old and the new is quite well developed elsewhere in the gospels: new wine in old wineskins. The relationship of the Old Covenant to the New.
The new wine represents the teachings of Jesus; the old wineskins, the law of Moses. In this verse, Jesus places value in both: out of his treasures, the householder which is instructed unto the kingdom of heaven brings both old and new.
John Chrysostom offers:
“Do you see how so far from excluding the Old Testament, he even commends it, and speaks publicly in favor of it, calling it a treasure?”
The new and old treasures are bound up one to another. Now, a teaching in parable form, while not unknown to Jesus’s listeners, was still a somewhat novel experience. Yet much of Jesus’s teaching was in this form of a new treasure. Further, much of His teaching was regarding the kingdom of heaven – again, something new for His listeners.
Conclusion
Jesus recognized the newness of his teaching, but at the same time, he did not tire of underlining his teachings’ continuity with the works of the prophets.
The Old Testament, in all its strictness and wisdom, was precious to Him. Jesus saw His teaching as an addition to this treasure. We see this in Hebrews:
Hebrews 1: Long ago, at many times and in many ways, God spoke to our fathers by the prophets, 2 but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world.
And here, where the apostle Paul is writing of Christ:
Colossians 2: 3 in whom are hidden all the treasures of wisdom and knowledge.