7 And yet so great are the tribulations, that even they who have trusted in Jesus, and who strive to persevere unto the end, greatly fear lest they fail; while Christ is treading the waves, and trampling down the world's ambitions and heights, the Christian is sorely afraid. Were not these things foretold him? Justly “they were afraid,” too, at seeing Jesus walking on the waves; like as Christians, though having hope in the world to come, are frequently disquieted at the crash of human affairs, when they see the loftiness of this world trampled down. They open the Gospel, they open the Scriptures, and they 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. Concerning whose loftiness it is foretold: “You shall destroy strongest cities,” and “the spears of the enemy have come to an end, and You have destroyed cities.” Why then are you afraid, O Christians? Christ speaks: “It is I; be not afraid.” Why are you alarmed at these things? Why are you afraid? I have foretold these things, I do them, they must necessarily be done. “It is I; be not afraid. Therefore they would receive Him into the ship.” Recognizing Him and rejoicing, they are freed from their fears. “And immediately the ship was at the land to which they went.” There is an end made at the land; from the watery to the solid, from the agitated to the firm, from the way to the goal.
8. “On the next day the multitude that stood on the other side of the sea,” whence the disciples had come, “saw that there was none other boat there, save that one whereinto His disciples were entered, and that Jesus went not with His disciples into the boat, but that His disciples had gone away alone; but there came other boats from Tiberias, near unto the place where they did eat bread, giving thanks to the Lord: when, therefore, the multitudes saw that Jesus was not there, nor His disciples, they also took shipping, and came to Capernaum seeking Jesus.” Yet they got some knowledge of so great a miracle. For they saw that the disciples had gone into the ship alone, and that there was not another ship there. But there came boats also from near to that place where they did eat bread; in these the multitudes followed Him. He had not then embarked with His disciples, and there was not another ship there. How, then, was Jesus on a sudden beyond the sea, unless that He walked upon the sea to show a miracle?
9. “And when the multitudes had found Him.” Behold, He presents Himself to the people from whom He had escaped into the mountain, afraid that He should be taken of them by force. In every way He proves to us and gives us to know that all these things are said in a mystery, and done in a great sacrament (or mystery) to signify something important. Behold, that is He who had escaped the crowds unto the mountain; is He not speaking with the same crowds? Let them hold Him now; let them now make Him a king. “And when they had found Him on the other side of the sea, they said unto Him, Rabbi, when camest Thou hither?”
Source: Tractates on the Gospel of John (New Advent)