John Calvin Commentary Acts 9:10

"Now there was a certain disciple at Damascus, named Ananias; and the Lord said unto him in a vision, Ananias. And he said, Behold, I [am here], Lord." — Acts 9:10 (ASV)

We have said before that this man was chosen more particularly than any of the apostles, so that Paul, having laid aside his puffed-up arrogance, might learn to listen to the humblest, and that he might come down from his excessive pride to the lowest position. And this vision was necessary for Ananias, so that he would not withdraw out of fear from the task assigned to him, namely, to teach Paul.

For though he knew that the Lord was calling him, yet he hesitated, or, at least, he made excuses. Therefore, it was necessary that he should have some definite proof of his calling, that successful results should be promised for his labor, and that he might undertake what the Lord commanded with a joyful and courageous spirit.

Furthermore, just as Christ encouraged and strengthened Ananias by appearing to him in the vision, so He prepared and made Paul ready for all things, so that he might receive Ananias reverently, as if he were receiving an angel coming from heaven. The Lord could have sent Paul straight to Ananias and shown him his house, but this was more fitting for Paul's confirmation, because he then knew more surely that the Lord cared for him.

And the Lord also shows His grace to us in this: that just as He stopped Paul before, so now He reaches out His hand to him willingly, through His minister. And, in the meantime, we are also taught by His example to be more ready and diligent in seeking out the lost sheep.

In a vision. This word vision signifies some light that was set before the eyes to testify to God’s presence. For this is the purpose of visions: that the majesty of the Word, being well established, may gain credibility among people. This kind of confirmation God often used with the prophets, as He says, that He speaks to His servants by a vision or by a dream. Indeed, He has allowed Satan to deceive unbelievers with false imaginations and apparitions. But because Satan’s deceptions only have power in darkness, God enlightens the minds of His children so that they become sure that they do not need to fear trickery. Therefore Ananias answered, Here am I, Lord, knowing indeed that it was God.