John Calvin on Acts 19:11-12

11. No small miracles. He calleth miracles virtutes or powers, after the common custom of the Scripture, which were testimonies of the extraordinary power of God. And showeth that Paul’s apostleship was set forth with these ensigns, that his doctrine might have the greater authority. For it is a common speech, That wonders and signs are showed by the hand of men. So that the praise thereof is ascribed to God alone as to the author; and man is only the minister. And that he may the more amplify the miracles, he saith that handkerchiefs and partlets “Semicinctia,” girdles. were brought unto the sick, which so soon as they touched they were healed. It is not unknown “Non obscurum est,” it is clear. to what end Paul had such power given him, to wit, that he might prove himself to be a true apostle of Christ, that he might make the gospel to be believed, and might confirm his ministry. And here it is expedient to call to mind those things which we had before, touching the lawful use of miracles. And whereas God did heal the sick with Paul’s handkerchiefs, it tended to that end, that even those who had never seen the man might, notwithstanding, reverently embrace his doctrine, though he himself were absent. For which cause the Papists are more blockish, who wrest this place unto their relics; as if Paul sent his handkerchiefs that men might worship them and kiss them “Oscularentur venerabundi homines,” men given to veneration might kiss them. in honor of them; as in Papistry, they worship Francis’ shoes and mantle, Rose’s girdle, Saint Margaret’s comb, and such like trifles. Yea, rather, he did choose most simple “Vilissimas,” most worthless. things, lest any superstition should arise by reason of the price or pomp. For he was fully determined to keep Christ’s glory sound and undiminished.

Acts 19:13-17

13. And certain of the vagabond Jews, exorcists, essayed to name over those which had evil spirits the name of the Lord Jesus, saying, We adjure you by Jesus whom Paul preacheth. 14. And there were certain sons of Sceva, a Jew, the chief of the priests, who did this. 15. And the evil spirit answered and said, Jesus I know, and Paul I know; but who are ye? 16. And the man in whom the evil spirit was ran upon them, and overcame them, and prevailed against them, so that they escaped out of that house naked and wounded. 17. And this was known to all both Jews and Grecians which dwelt at Ephesus; and fear came upon them all, and the name of the Lord Jesus was magnified.