John Calvin on John 1:43

43. Follow me. When Philip was inflamed by this single word to follow Christ, we infer from it how great is the efficacy of the word of God; but it does not appear indiscriminately in all, for God addresses many without any advantage, just as if he struck their ears with a sound which vanished into air. So then the external preaching of the word is in itself unfruitful, except that it inflicts a deadly wound on the reprobate, so as to render them inexcusable before God. But when the secret grace of God quickens it, all the senses must be affected in such a manner that men will be prepared to follow wherever God calls them. We ought, therefore, to pray to Christ that he may display in us the same power of the Gospel. In the case of Philip, there was no doubt a peculiarity about his following Christ; for he is commanded to follow, not like one of us, but as a domestic, and as a familiar companion. But still the calling of all of us is illustrated by this calling of Philip.