John Calvin on Acts 8:25

25. And they testified. In these words Luke teacheth that Peter and John came not only that they might enrich the Samaritans with the gifts of the Spirit, but also that they might establish them in the faith which they had already received, by approving Philip’s doctrine. For thus much doth the word testify import; as if he should say, that it came to pass by their testimony, that the word of God had full and perfect authority, and that the truth was of force, as being well testified and authentic. Notwithstanding Luke teaeheth therewithal that they were faithful witnesses of God, when he addeth that they uttered the word of God. This was, therefore, the sum of the apostles’ doctrine, faithfully to utter those things which they had learned of the Lord, and not their own inventions, or the inventions of any man else. He saith, that they did this not only in the city, but also in villages. Therefore we see that they were so inflamed to further the glory of Christ, that whithersoever they came they had him in their mouth. So that the seed of life began to be sown throughout the whole region, after that it was preached in the city. “Ab una urbe,” from one city.

Acts 8:26-31

26. And an angel of the Lord spake to Philip, saying, Arise, and go toward the south, to the way which goeth down from Jerusalem to Gaza; it is waste. 27. And when he arose, he went. And, behold, a man, an Ethiopian, an eunuch, a man of great authority with Candace, queen of Ethiopia, which had the rule of all her treasure, which carne [had come] to Jerusalem to worship 28. And as he returned, and sat in his chariot, he read Esaias the prophet. 29. And the Spirit said to Philip, Draw near, and be thou joined to this chariot. 30. And as Philip ran unto it, he heard him reading the prophet Esaias, and he said, Understandest thou what thou readest? 31. He said, How can I, unless some man direct me? And he requested Philip that he would come up and sit with him.