Praise be to Jesus and Mary, now and forever.
Both of today's readings are taken from farewell discourses. Both especially regard the pastors of the Church. St. Paul is speaking to them, and Christ is praying for them. Both speak of the unity of Christians in truth and of the blood of Christ, which is the price of this unity.
Christ prays that Christians may be one, and St. Paul warns against the savage wolves that undermine their unity. St. Paul says that the Church was paid for with the blood of Christ, and Christ says, "I consecrate myself for them so that they also may be consecrated in truth," thus referring to His sacrifice. Before we look at some of these points in more detail, let's step back and recall the context of these two readings.
St. Paul is speaking to the leaders of the Church of Ephesus, whom he calls both presbyters and overseers. Presbyter is the word from which the English word priest derives. Overseer is a generic translation of the Greek word episkopos, from which we get the word bishop. From the fact that St. Paul uses the words interchangeably, we can see that at the time, these two words were essentially synonyms. Although there is a sacramental difference between priests and bishops, the Church did not immediately have distinct words to express this difference. It took time to settle on the right words to express what faith believed.
The word translated as presbyter could also be translated as elder. This is a Semitic name for the leaders of the Church. As Israel's leaders were called elders, so the name for the leaders of the new Israel, the Church, is elders or presbyters. But because Christ instituted the priesthood at the Last Supper when He said, "Do this in memory of me," there is an essential difference in the new Israel, which is that the elders of the new Israel, the presbyters, are priests. The other word, translated as overseer or bishop, is a Hellenistic name for the leaders of the Church. Because the Church had both a Semitic background from the Jews and a Hellenistic background from the Greeks, it had these two different words for its leaders.
When St. Paul was speaking to the leaders of the Church of Ephesus, the two words were used interchangeably. Half a century later, St. Ignatius made a clear distinction between the two words, using presbyter for priests and episkopos for bishops. The Church leaders who came from Ephesus were, therefore, at least priests, but, as St. Bede observes, at most one was a bishop, because the Church in a city is led by a single bishop.
However, it's possible that not even one of them was a bishop, because the bishops are the successors of the apostles, and we don't know exactly when the first bishops were ordained. It might not have seemed necessary yet to ordain a successor to the apostles for Ephesus. St. Paul called these priests and the bishop, if there was one, to come to see him for the last time at the port before he went on his way to Jerusalem. He was going there because that's where God wanted him to go, and he didn't know what was going to happen to him there, but the Holy Spirit had made it clear to him that it at least involved being a prisoner.
He might be going to martyrdom. We know now that he wasn't, but he was going to spend a couple of years as a prisoner. And there's a lesson here about the way God thinks, which is very different from the way that we think. God had a holy and zealous apostle who was ready to go anywhere and face anything in order to spread the gospel. And God thought that it would be better for him to spend the next couple of years in jail. This would not be my plan, but it was God's, and God is wiser than we are.
In jail, St. Paul would win the grace of conversion for many people by offering his sufferings. From that jail, he would be going to Rome in chains. This prisoner would free those held captive by sin, and he would, in this way, while deprived of his freedom, have the freedom to reach Rome, and thus the heart of the empire.
Yesterday, we heard the first half of what St. Paul said to the priests of Ephesus. He spoke about what he had done and told them that they would never see his face again, and this made them very sad, as we heard, but they had to be prepared for what was coming. In today's reading, he tells them more, including what the Holy Spirit has revealed to him about their future, about their future trials.
The main reason why St. Paul talks about what he did when he was in Ephesus is to remind them of the example that he gave them to follow. Turning our attention to the gospel, we find Jesus is not addressing the apostles but offering a high priestly prayer to the Father. This prayer has three parts. In the first, He prays for Himself. In the second, He prays for the disciples He sends to evangelize, the apostles, and finally for those who will believe through their ministry.
Yesterday, we heard the first part and the beginning of the second part. Today, we heard the rest of the second part, and tomorrow, we will hear the third part. Christ is leaving the world and is leaving His apostles in the world to evangelize. So, like St. Paul, He's getting ready for them to take over the mission, getting them ready for this, but in today's gospel, He's doing this by prayer rather than by teaching. He's praying particularly for the protection and unity of His disciples, and His prayer cannot fail to be heard, for it is God Himself who prays.
And even as man, His will is perfectly united to God. So what He asks for is what God wishes to grant. Scholars call this a high priestly prayer because Jesus is offering a sacrifice. This is what He means when He says, "I consecrate myself for them so that they also may be consecrated in truth." To consecrate something is to set it apart for a holy purpose. And the word that Jesus uses could also be translated sanctify or make holy.
In the Old Testament, the sacrifices were said to be made holy when they were offered to God. Thus, St. John Chrysostom explains Jesus' words as, "I offer myself in sacrifice for them, so that they also may be sanctified in truth." And so Christ says this, since of old, sanctification was prefigured in the Lamb, and now it was not merely in figure but in truth, so they are sanctified in truth. He therefore said that they also may be sanctified in thy truth. I say this, for I consecrate them to thee and offer them to thee.
So, St. Paul reminds the priests of Ephesus, you tend the Church of God that He acquired with His own blood by offering Himself as a sacrifice. St. Paul can speak of the blood of God because Christ, who shed His blood, is God. Two natures are united in one person. This is the astounding price that God paid for the Church, and if it is worth so much to Him, how will He feel about pastors who do not guard it diligently?
St. Paul thus reminds the priests of Ephesus how seriously they must take their task. Furthermore, their duty to guard the flock is not in vain. The danger is very real. Not only will savage wolves come among you and not spare the flock, but even from your own group, men will come forward, perverting the truth to draw the disciples away after them.
Who are these savage wolves? The book of Revelation gives us a hint. It contains a letter that Christ tells St. John to send to the Church of Ephesus, in which we read, "I know your works, your toil, and your patient endurance, and how you cannot bear with those who are evil, but have tested those who call themselves apostles and are not, and found them to be false." So we see that the priests of Ephesus kept a good guard. They recognized these false apostles.
The savage wolves could be these false apostles, such as Judaizers who went around teaching that Christians have to observe the whole law of Moses. Regarding the heretics who came from among the Christians of Ephesus, we know what St. Paul later wrote to St. Timothy. He told him, "Remain at Ephesus so that you may charge certain persons not to teach any different doctrine, nor to devote themselves to myths and endless genealogies, which promote speculations rather than the stewardship from God that is by faith."
These were people who desired to be teachers of the law. They were looking to be famous, to be respected by people, and yet they did not understand either what they were saying or the things about which they made such confident assertions. They were people who claimed to be experts who understood mysteries, but they were really just spouting nonsense.
And this sounds like the Gnostics or the proto-Gnostics who mingled Christianity with occultism, claiming to explain secrets that would get you into heaven, as indeed some do even today. Christian unity is based on the acceptance of the fullness of the truth taught by Christ.
And thus St. Paul said, "I commend you to God and to that gracious word of His that can build you up and give you inheritance among all those who are consecrated." And Christ likewise prayed, "Consecrate them in the truth. Your word is truth." Let us stand firm in this truth, stand firm in the truth taught by the Magisterium. 
Praised be Jesus and Mary, now and forever.