17. I have then, etc. After having in general commended his own calling, that the Romans might know that he was a true and undoubted apostle of Christ, he now adds testimonies, by which he proved that he had not only taken upon him the apostolic office conferred on him by God’s appointment, but that he had also eminently adorned it. He at the same time records the fidelity which he had exhibited in discharging his office. It is indeed to little purpose that we are appointed, except we act agreeably to our calling and fulfill our office. He did not make this declaration from a desire to attain glow, but because nothing was to be omitted which might procure favor and authority to his doctrine among the Romans. In God then, not in himself, did he glory; for he had nothing else in view but that the whole praise should redound to God.
And that he speaks only negatively, it is indeed an evidence of his modesty, but it availed also to gain credit to what he was proceeding to announce, as though he said, “The truth itself affords me such cause for glowing, that I have no need to seek false praises, or those of another, I am content with such as are true.” It may be also that he intended to obviate the unfavorable reports which he knew were everywhere scattered by the malevolent, he therefore mentioned beforehand that he would not speak but of things well known.