The Lord says, “All things are delivered to me by the Father.” … But in the “all things” [it is implied that] nothing has been kept back [from him], and for this reason the same person is the Judge of the living and the dead; “having the key of David: he shall open, and no man shall shut: he shall shut, and no man shall open.” For no one was able, either in heaven or in earth, or under the earth, to open the book of the Father, or to behold him, with the exception of the Lamb who was slain and who redeemed us with his own blood, receiving power over all things from the same God who made all things by the Word, and adorned them by [his] Wisdom, when “the Word was made flesh”; that even as the Word of God had the sovereignty in the heavens, so also might he have the sovereignty in earth, inasmuch as [he was] a righteous man, "who did not sin, neither was there found guile in his mouth"; and that he might have the preeminence over those things that are under the earth, he himself being made “the first-begotten of the dead”; and that all things, as I have already said, might behold their King; and that the paternal light might meet with and rest upon the flesh of our Lord, and come to us from his resplendent flesh, and that thus humanity might attain to immortality, having been invested with the paternal light.
"Lo, the Lion of the tribe of Judah, the root of David, hath prevailed." We read in Genesis that this lion of the tribe of Judah hath conquered, when the patriarch Jacob says, "Judah, thy brethren shall praise thee; thou hast lain down and slept, and hast risen up again as a lion, and as a lion's whelp." For He is called a lion for the overcoming of death; but for the suffering for men He was led as a lamb to the slaughter. But because He overcame death, and anticipated the duty of the executioner, He was called as it were slain. He therefore opens and seals again the testament, which He Himself had sealed. The legislator Moses intimating this, that it behoved Him to be sealed and concealed, even to the advent of His passion, veiled his face, and so spoke to the people; showing that the words of his announcement were veiled even to the advent of His time. For he himself, when he had read to the people, having taken the wool purpled with the blood of the calf, with water sprinkled the whole people, saying, "This is the blood of His testament who hath purified you." It should therefore be observed that the Man is accurately announced, and that all things combine into one. For it is not sufficient that that law is spoken of, but it is named as a testament. For no law is called a testament, nor is any thing else called a testament, save what persons make who are about to die. And whatever is within the testament is sealed, even to the day of the testator's death. Therefore it is with reason that it is only sealed by the Lamb slain, who, as it were a lion, has broken death in pieces, and has fulfilled what had been foretold; and has delivered man, that is, the flesh, from death, and has received as a possession the substance of the dying person, that is, of the human members; that as by one body all men had fallen under the obligation of its death, also by one body all believers should be born again unto life, and rise again. Reasonably, therefore, His face is opened and unveiled to Moses; and therefore He is called Apocalypse, Revelation. For now His book is unsealed-now the offered victims are perceived-now the fabrication of the priestly chrism; moreover the testimonies are openly understood.
The Son of man is said to have received the book from the right hand of God as both the dispensation from the Father and an arrangement from himself, for each reigns upon the throne with the Holy Spirit. And also here we ought understand the right hand to represent the blessedness of the victory. Nor ought it be understood in a fleshly manner as though he received the book from another hand of the Father, since the self-same is Son of the Father and the self-same the right hand [of God]. But since he who said, “Rejoice, for I have overcome the world,” always conquers in those who belong to him, he also makes his own church to exist as a conqueror, and it is declared of her that she receives the book.
To be sure, the Lamb is the assumed man who for our salvation willingly offered himself over to death. Worthily he received the scroll, that is, the power of all the works of God, and from the right hand of him who is seated on the throne, that is, he received all things from God the Father, as he himself said: “All which the Father has is mine.” Then did he receive this scroll, when rising from the dead he showed the mystery of the Trinity, which had been hidden from the ages, and revealed it to the world.
And he came and took the book out of the right hand of Him who sat on the throne. The book from the right hand of God, the dispensation itself of the Incarnation, is said to have been received by the Son of Man from the Father and from Himself, according to what He is as God, because both, along with the Holy Spirit, dwell on the throne. For Christ, who is the Lamb in humanity, is Himself the right hand of the Father in Deity.
And he came and took the book out of the right hand of him that sat on the throne. The right hand of him that sits on the throne is the same as the Lamb as it were slain in the midst of the throne, because the Son of God through whom the world was created and the Son of man through whom man was redeemed are not two, but one Christ. Therefore the Lamb, that is the Son of man, took the book, that is the plan for the salvation of man, to which every page of the Scriptures bears witness, from himself, that is from his divinity.
And He came and took, that is the little scroll, from the right hand of the One seated on the throne. Therefore, when all those in heaven and on earth, and under the earth, wondered to open the little scroll or to look into it as it had been seen before, only Christ, the Son of God, who for us and through us became and remains what He was, took the little scroll.
[AD 202] Irenaeus on Revelation 5:7