17 And entered into a ship, and went over the sea toward Capernaum. And it was now dark, and Jesus was not come to them.
[AD 407] John Chrysostom on John 6:15-21
(Hom. xlii. 3) See what the belly can do. They care no more for the violation of the Sabbath; all their zeal for God is fled, now that their bellies are filled: Christ has become a Prophet, and they wish to enthrone Him as king. But Christ makes His escape; to teach us to despise the dignities of the world. He dismisses His disciples, and goes up into the mountain.— (Hom. xliii. 1). These, when their Master had left them, went down in the evening to the sea; as we read; And when even was now come, His disciples went down unto the sea. They waited till evening, thinking He would come to them; and then, as He did not come, delayed no longer searching for Him, but in the ardour of love, entered into a ship, and went over the sea toward Capernaum. They went to Capernaum thinking they should find Him there.

(Hom. xlii. 1) The mention of the time is not accidental, but meant to show the strength of their love. They did not mate excuses, and say, It is evening now, and night is coming on, but in the warmth of their love went into the ship. And now many things alarm them: the time, And it was now dark; and the weather, as we read next, And the sea arose by reason of a great wind that blew; their distance from land, So when they had rowed about five and twenty or thirty furlongs.

(Hom. xliii. 1) And at last He appears quite unexpectedly: They see Jesus walking upon the sea, drawing nigh. He reappears after His retirement, teaching them what it is to be forsaken, and stirring them to greater love; His reappearance manifesting His power. They were disturbed, were afraid, it is said. Our Lord comforts them: But He saith unto them, It is I, be not afraid.

(Hom. xliii. s. 1) He appeared to them in this way, to show His power; for He immediately calmed the tempest: Then they wished to receive Him into the ship; and immediately the ship was at the land, whither they went. So great was the calm, He did not even enter the ship, in order to work a greater miracle, and to show his Divinity more clearlyg.

(Hom. xliii. 1) Jesus does not show Himself to the crowd walking on the sea, such a miracle being too much for them to hear. Nor even to the disciples did He show Himself long, but disappeared immeditately.

(Hom. xliii. 1) Or take another explanation. This miracle seems to me to be a different one, from the one given in Matthew: for there they do not receive Him into the ship immediately, whereas here they doh: and there the storm lasts for some time, whereas here as soon as He speaks, there is a calm. He often repeats the same miracle in order to impress it on men's minds.

[AD 735] Bede on John 6:15-21
The multitude concluding, from so great a miracle, that He was merciful and powerful, wished to make Him a king. For men like having a merciful king to rule over them, and a powerful one to protect them. Our Lord knowing this, retired to the mountain: When Jesus therefore perceived that they would come and take Him by force to make Him a king, He departed again into a mountain Himself alone. From this we gather, that our Lord went down from the mountain before, where He was sitting with His disciples, when He saw the multitude coming, and had fed them on the plain below. For how could He go up to the mountain again, unless He had come down from it.

(in v. cap. Joan.) The way of speaking we use, when we are in doubt; about five and twenty, we say, or thirty.

(in Matt. c. xiv.) He does not say, I am Jesus, but only I am. He trusts to their easily recognising a voice, which was so familiar to them, or, as is more probable, He shows that He was the same who said to Moses, I am that I am (Exod. 3:14)

This ship, however, does not carry an idle crew; they are all stout rowers; i. e. in the Church not the idle and effeminate, but the strenuous and persevering in good works, attain to the harbour of everlasting salvation.

[AD 804] Alcuin of York on John 6:15-21
Baskets are used for servile work. The baskets here are the Apostles and their followers, who, though despised in this present life, are within filled with the riches of spiritual sacraments. The Apostles too are represented as baskets, because, that through them, the doctrine of the Trinity was to be preached in the four parts of the world. His not making new loaves, but multiplying what there were, means that He did not reject the Old Testament, but only developed and explained it.

[AD 1107] Theophylact of Ohrid on John 6:15-21
Observe the three miracles here; the first, His walking on the sea; the second, His stilling the waves; the third, His putting them immediately on shore, which they were some distance off, when our Lord appeared.

When either men or devils try to terrify us, let us hear Christ saying, It is I, be not afraid, i. e. I am ever near you, God unchangeable, immoveable; let not any false fears destroy your faith in Me. Observe too our Lord did not come when the danger was beginning, but when it was ending. He suffers us to remain in the midst of dangers and tribulations, that we may be proved thereby, and flee for succour to Him Who is able to give us deliverance when we least expect it. When man's understanding can no longer help him, then the Divine deliverance comes. If we are willing also to receive Christ into the ship, i. e. to live in our hearts, we shall find ourselves immediately in the place, where we wish to be, i. e. heaven.

[AD 430] Augustine of Hippo on John 6:17-18
He fled alone to the mountain—the first begotten from the dead—because he has ascended above all the heavens and is interceding for us. … But while he was above what were the disciples enduring in the ship below? For that ship prefigured the church while he is on high.…While they were sailing to [Capernaum], John tells us what happened to them. It became dark and Jesus had not come to them. It was right that John said it was dark, because the light [Jesus] had not yet come to them. As the end of the world draws near, errors increase, terrors multiply, iniquity abounds and infidelity escalates. Light, again, is love according to John. Whoever hates his brother is in darkness. … The waves and storms and winds then that agitate the ship, are the clamors of hurtful speech and love waxing cold.… Nevertheless the wind, and storm, and waves, and darkness were not able to stop and sink the vessel. For the one who endures to the end shall be saved.…
And how does Jesus come to the disciples? He comes walking upon the waves, keeping all the swellings of the world under his feet, pressing down all of humanity’s pride. And so it continues, so long as time endures, so long as the ages roll. Tribulations increase, all these swell and mount up: Jesus passes on treading upon the waves. And yet, so great are the tribulations that even those who have trusted in Jesus and who strive to persevere to the end greatly fear lest they fail.… But they open the gospel, they open the Scriptures and find all these things there foretold; that this is the Lord’s doing. He tramples down the heights of the world that he may be glorified by the humble.

[AD 444] Cyril of Alexandria on John 6:17-18
The circumstances of their journey drive the disciples to a more intense search for the Savior. For the deep darkness of the night troubles them, hovering like smoke on the raging waves and taking away any ability for navigation. The fierce winds, riding on the waves with a rushing sound that raises the billows high above their heads, had to trouble them more than a little bit. Yes, and through all of this, John records, “Jesus was not yet with them.” This was the real danger, and Christ’s absence from these voyagers was making their fear grow more and more.Those who are not with Jesus are in a fierce tempest of a storm. They are cut off from him or at least seem to be absent from him because they have departed from his holy laws. Because of their sin they are separated from the one who is able to save. If then it is overwhelming to be in such spiritual darkness, if it is oppressive to be swamped by the bitter sea of pleasures, let us then receive Jesus. For this is what will deliver us from dangers and from death in sin.

[AD 491] Isaiah the Solitary on John 6:17-18
Like a pilot steering a boat through the waves, one should hold to the course, guided by grace. Keeping his attention fixed within himself, he should commune with God in stillness, guarding his thoughts from distraction and his intellect from curiosity.In storms and squalls we need a pilot, and in this present life we need prayer, for we are susceptible to the provocations of our thoughts, both good and bad. If our thought is full of devotion and love of God, it rules over the passions.