John Chrysostom
Why was there a vision, and why did the Holy Spirit not command directly? He wished to draw them in this way also.
The saints also had visions, and Paul himself at the beginning saw in a vision a man who came and laid his hand upon him; Acts 9:12.
He moved him to go there so that the preaching might spread.
For this reason also he was forbidden to remain in other cities, when Christ moved him to go there.
Those others were going to hear John, and for a long time, and perhaps they did not have such great need. But it was necessary to come there.
Then he also departs, setting out to the other side of the sea. Notice, it is not through an angel, as with Philip or Cornelius.
How then? The Lord appears to him in a vision, only in human form and not in divine form.
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Where persuasion was easy, He appears in a more human manner. Where it was more difficult, He appears in a more divine manner.
Thus, when he was merely being drawn to preach, for this a dream was given him. But when he had to be restrained from preaching, the Holy Spirit reveals it.
So it was also with Peter, when the Spirit said to him, “Rise, go down”; Acts 10:20.
The Spirit did not perform the easier matters, for a dream was sufficient for this. So also with Joseph: when he was easy to persuade, there was a dream; to others, a vision; Mt 2:13.
So also with Cornelius and with Paul himself.
And behold, says the writer, “a certain man, a Macedonian, stood and begged him, saying.” He did not say, “commanding,” but “begging,” concerning those who needed healing.