John 15:27

"And ye also," He says," shall bear witness, because ye have been with me from the beginning." The Holy Spirit shall bear witness, and so also shall ye. For, just because ye have been with me from the beginning, they can preach what ye know; which ye cannot do at present, because the fullness of that Spirit is not yet present within you. "He therefore shall testify of me, and ye also shall bear witness:" for the love of God shed abroad in your hearts by the Holy Spirit, who shall be given unto you, will give you the confidence needful for such witness-bearing. And that certainly was still wanting to Peter, when, terrified by the question of a lady's maid, he could give no true testimony; but, contrary to his own promise, was driven by the greatness of his fear thrice to deny Him. But there is no such fear in love, for perfect love casteth out fear. In fine, before the Lord's passion, his slavish fear was questioned by a bond-woman; but after the Lord's resurrection, his free love by the very Lord of freedom: and so on the one occasion he was troubled, on the other tranquillized; there he denied the One he had loved, here he loved the One he had denied. But still even then that very love was weak and straitened, till strengthened and expanded by the Holy Spirit. And then that Spirit, pervading him thus with the fullness of richer grace, kindled his hitherto frigid heart to such a witness-bearing for Christ, and unlocked those lips that in their previous tremor had suppressed the truth, that, when all on whom the Holy Spirit had descended were speaking in the tongues of all nations to the crowds of Jews collected around, he alone broke forth before the others in the promptitude of his testimony in behalf of the Christ, and confounded His murderers with the account of His resurrection. And if any one would enjoy the pleasure of gazing on a sight so charming in its holiness, let him read the Acts of the Apostles: and there let him be filled with amazement at the preaching of the blessed Peter, over whose denial of his Master he had just been mourning; there let him behold that tongue, itself translated from diffidence to confidence, from bondage to liberty, converting to the confession of Christ the tongues of so many of His enemies, not one of which he could bear when lapsing himself into denial. And what shall I say more? In him there shone forth such an effulgence of grace, and such a fullness of the Holy Spirit, and such a weight of most precious truth poured from the lips of the preacher, that he transformed that vast multitude of Jews who were the adversaries and murderers of Christ into men that were ready to die for His name, at whose hands he himself was formerly afraid to die with his Master. All this did that Holy Spirit when sent, who had previously only been promised. And it was these great and marvellous gifts of His own that the Lord foresaw, when He said, "They have both seen and hated both me and my Father: that the word might be fulfilled that is written in their law, They hated me without a cause. But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, who proceedeth from the Father, He shall testify of me: and ye also shall bear witness." For He, in bearing witness Himself, and inspiring such witnesses with invincible courage, divested Christ's friends of their fear, and transformed into love the hatred of His enemies.

Which Paul doth also. For when many wondered how that the Jews believed not, he brings in Prophets foretelling it of old, and declaring the cause; that their wickedness and pride were the cause of their unbelief. "Well then; if they kept not Thy saying, neither will they keep ours; if they persecuted Thee, therefore they will persecute us also; if they saw signs, such as none other man wrought; if they heard words such as none other spake, and profited nothing; if they hate Thy Father and Thee with Him, wherefore," saith one, "hast Thou sent us in among them? How after this shall we be worthy of belief? which of our kindred will give heed to us?" That they may not therefore be troubled by such thoughts, see what sort of comfort he addeth. "When the Comforter is come, whom I will send unto you from the Father, even the Spirit of Truth, which proceedeth from the Father, He shall testify of Me. And ye also shall bear witness, because ye have been with Me from the beginning." "He shall be worthy of belief, for He is the Spirit of Truth." On this account He called It not "Holy Spirit," but "Spirit of Truth." But the, "proceedeth from the Father," showeth that He knoweth all things exactly, as Christ also saith of Himself, that "I know whence come and whither I go", speaking in that place also concerning truth. "Whom will send." Behold, it is no longer the Father alone, but the Son also who sendeth. "And ye too," He saith, "have a right to be believed, who have been with Me, who have not heard from others." Indeed, the Apostles confidently rely on this circumstance, saying, "We who did eat and drink with Him." And to show that this was not merely said to please, the Spirit beareth witness to the words spoken.