John ascended to heaven. How did he do this? "After this I looked, and there before me was a door standing open in heaven. And the voice I had first heard speaking to me like a trumpet said, “Come up here, and I will show you what must take place after this.” Revelation 4

In John, we are told many times that Jesus spoke the words of God the Father. Moses ascended to the high places on the mountain and then descended with the words of God. This is the background to Jesus' discussion with Nicodemus, a teacher of the Law. The context of John 3:13 tells us this what Jesus is talking about. When the Spirit dwells in you, heaven is open to you and you have access to God just as Moses spoke with God. Jesus speaks of things he receives in the Spirit of God.