Image via Wikipedia
The Lord of all gave to His apostles the power of the gospel, and by them we also have learned the truth, that is, the teaching of the Son of God - as the Lord said to them, `He who hears you hears Me, and he who despises you despises Me, and Him Who sent Me' [Lk.10:16]. For we learned the plan of our salvation from no other than from those through whom the gospel came to us. The first preached it abroad, and then later by the will of God handed it down to us in Scriptures, to be the foundation and pillar of our faith. For it is not right to say that they preached before they had come to perfect knowledge, as some dare to say, boasting that they are the correctors of the apostles. For after our Lord had risen from the dead, and they were clothed with the power from on high when the Holy Spirit came upon them, they were filled with all things and had perfect knowledge. They went out to the ends of the earth, preaching the good things that come to us from God, and proclaiming peace from heaven to all men, all and each of them equally being in possession of the gospel of God.
St. Irenaeus, Against the Heresies, III