Jesus had to ascend to Heaven so that His Spirit may come upin and dwell in each of us. It is about one glorified resurrected body of Jesus versus Jesus' presence to everyone else through the indwelling of the Holy Spirit. It is about one Jesus preaching and witnessing versus everyone of us preaching and witnessing in His name and through the power of His Spirit. (John 20:19-23, Solemnity of the Pentecost B)