John Calvin on Acts 8:7

7. Unclean spirits. He toucheth certain kinds briefly, that we may know with what miracles they “Samaritae,” the Samaritans. were brought to attribute any authority to Philip. That crying wherewith the unclean spirits cried was a token of resistance. Wherefore this served not a little to set forth the power of Christ, that he did bind the devils with his commandment, though they resisted stubbornly.