John Calvin on Acts 9:1

1. And Saul. Luke setteth down in this place a noble history, and a history full well worthy to be remembered, concerning the conversion of Paul; after what sort the Lord did not only bring him under, and make him subject to his commandment, when he raged like an untamed beast but also how he made him another and a new man. But because Luke setteth down all things in order as in a famous work of God, it shall be more convenient to follow his text, [context,] that all may come in order whatsoever is worth the noting. When as he saith, that he breathed out threatenings and slaughter as yet, his meaning is, that after that his hands were once imbued with innocent blood, he proceeded in like cruelty, and was always a furious and bloody enemy to the Church, after that he had once made that entrance “Ab infausto trocinio,” from that ominous commencement. whereof mention is made in the death of Stephen. For which cause it was the more incredible that he could be so suddenly tamed. And whereas such a cruel wolf was not only turned into a sheep, but did also put on the nature of a shepherd, the wonderful hand of God did show itself therein manifestly.