Summary: After being in the Spirit the apostle John was invited to "Come Up Hither" to the throne of God.
The apostle John had spent his life preaching the gospel and in his old age, about 62 years after the cruxificion, he had been banished to the isle of Patmos. He gives the reason for his imprisonment, "For the word of God and the testimony of Jesus Christ."
Life was not easy in this Roman penal colony in the Aegean sea. The terrain was rugged and the prisoners were forced to work the mines of the island. I doubt that John had the day off, but this did not stop the apostle from worship on the Lord’s day. Perhaps his mind went back to another Lord’s day, many years earlier when he outran the apostle Peter, to look into the empty tomb of the Lord. He remembered the Lord appearing and showing the scars of his hands and feet. He had been instructed for 40 days by the risen Christ, who gave commandments concerning the kingdom of God. John had seen the ascension, and was present at the outpouring of the Holy Ghost on the day of Pentecost. He stood with Peter as he addressed the mocking crowd and proclaimed that the Jesus they had slain had been made both Lord and Christ.
Today was the Lord’s day and regardless of conditions, John was in the Spirit. Suddenly he heard the voice of the Eternal. The voice that had framed the worlds by a spoken Word, who had stretched forth the heavens alone by Himself. The voice that shook the mountains at the giving of the law. He heard the voice of the Alpha and Omega, the Beginning and the Ending, the First and the Last. The One who had always proclaimed Himself to be the One and only God who knew no others, either, before, beside, or after Himself.
John turned and saw a form that was similar to that of the Lord Jesus whom he had known . As he states in I John 1:1 (quickview)  he saw," That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life."
The Deity was no longer veiled. It was shinning through the Lord Jesus, just as it did on the mountain of transfiguration, but to a greater extent.
13 And in the midst of the seven candlesticks one like unto the Son of man, clothed with a garment down to the foot, and girt about the paps with a golden girdle.
14 His head and his hairs were white like wool, as white as snow; and his eyes were as a flame of fire;
15 And his feet like unto fine brass, as if they burned in a furnace; and his voice as the sound of many waters.
16 And he had in his right hand seven stars: and out of his mouth went a sharp twoedged sword: and his countenance was as the sun shineth in his strength.
17 And when I saw him, I fell at his feet as dead. And he laid his right hand upon me, saying unto me, Fear not; I am the first and the last:
18 I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
John was in the Spirit. No great cathedral, no mass choir, no driving musical beat. Nobody present to work him into a state of hysteria. Just him and the Lord. To us, this would be the ultimate experience, and yet John was invited to , "Come Up Hither." There is always a higher realm, a higher experience in the Lord. Just as the apostle Paul stated that he had not obtained, and had expressed a desire to know Him, John was being elevated to yet another plane in the Spirit. He was taken to the throne of God. Here he saw the Godhead embodied in the Lord Jesus Christ. He saw myriads of redeemed people of every kindred, tongue, nation and people, prasing the Lamb, who had redeemed them by His blood, to be kings and priests unto God. Somewhere in this vast multitude, John saw you and me.