"Received . . . from man" means something quite different from "according to man" in verse 11. The former is a technical phrase that we would not tend to recognize, indicating a process of memorization. A Jew of Paul's day would have understood this, as it was the method by which rabbis passed along rabbinic traditions to their students. They would walk along, or be sitting around the campfire, and the rabbi would instruct by getting his disciples to recite back to him what he had said. Since they did not have books as we do, and the scrolls were awkward to carry around, they memorized teachings, poetry, and songs, and passed them on. Everything was learned by rote. One can imagine the rigid personality this would tend to produce.
But the apostle Paul says, "My gospel did not come in this way at all." It was revealed to him: ". . . but it came through the revelation of Jesus Christ."
"Nor was I taught it" is different from both "neither received it from man" or "according to man." "Nor was I taught it" indicates the normal type of instruction was not the way he received it either. The normal type of instruction is the way we receive it, in a classroom or church situation in which a teacher or preacher teaches or lectures.
However, Paul claims, "I did not learn it that way. It came by revelation!" Jesus Christ miraculously gave it to him in person—just as He gave it to the Twelve. Paul received it by direct revelation. Thus, in Galatians 1:10-12, he relates that he had a distinctive, revelatory experience paralleled only by the Twelve. And what was revealed to Paul has subsequently been revealed to us because Paul teaches it to us through his words.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part 24)