Now when they heard this, they were pricked in their hearts, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
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Augustine of Hippo
For on the sending down of the Holy Spirit after the Lord’s passion, and resurrection, and ascension, when miracles were being done in the name of Him whom, as if dead, the persecuting Jews had despised, they were pricked in their hearts; and they who in their rage slew Him were changed and believed; and they who in their rage shed His blood, now in the spirit of faith drank it; they acknowledged their sin, they learned something of the Apostle, that they might not despair of the pardon of the Preacher. ...
And when the multitudes exclaimed, "What shall we do then? "Peter says to them, "Repent, and be baptized everyone of you in the name of Jesus for the remission of sins, and ye shall receive the gift of the Holy Spirit."
Do you see what a great thing gentleness is? More than any vehemence, it pricks our hearts, inflicts a keener wound. For as in the case of bodies which have become callous, the man that strikes upon them does not affect the sense so powerfully, but if he first mollify them and make them tender, then he pierces them effectually; so in this instance also, it is necessary first to mollify. But that which softens, is not wrath, not vehement accusation, not personal abuse; it is gentleness. The former indeed rather aggravate the callousness, this last alone removes it. If then you are desirous to reprove any delinquent, approach him with all possible mildness. For see here; he gently reminds them of the outrages they have committed, adding no comment; he declares the gift of God, he goes on to speak of the grace which bore testimony to the event, and so draws out his discourse to a still greater length. So they stood in awe of the gentleness of Peter, in that he, speaking to men who had cru...