The first thing that John sees after the horrifying scenes and sequences of chapter 13, is the Lamb of God, who is "standing", that is, in position of action, on Mount Zion; that is, in action of authority and power. We know from the Word that Sion does not only correspond to the geographical place on this earth; that is, the earthly Jerusalem, but first with Heaven, with the holy city, the new Jerusalem, the heavenly one. We read like this in Hebrews 12:22; "But you have come near to Mount Zion, to the city of the living God, Jerusalem the heavenly one, to the company of many thousands of angels." As we can see in the context of this section, this mountain of Sion is the one that corresponds to the one that is located in Heaven. As we will analyze in chapter 21, we believe that this heavenly city is to descend from heaven, from God, and come to be the tabernacle of God with men (21: 2, 3), so it is feasible that at the time of fulfillment of what is expressed in this verse, said holy city, is literally coming to this planet. Together with the Lamb, that is, the expression of the Christ who gave his life for all, there are 144,000 sealed with two names: that of the Lamb and the of His Father in the forehead. What a difference it is to have the seal of the living God on the forehead, instead of the seal or mark of the Devil's Beast in the same place! The difference lies between eternal life or death. : Those who will sing are those 144,000. They will not do it on earth, but before the Throne of God. They will also sing before the four living beings mentioned in chapter four, which are around and around the Throne. They will also sing to the elders; it means the twenty-four elders mentioned also in chapter four, who are also sitting around the Throne. However, no one of them, or anyone else can learn that song, only the 144,000 who sing it, who will be rescued or bought by the blood of Christ from the rest of the earth. Obviously, their song, which is new, will have to do with them, since only they can learn it.