Revelation 10:8

And I heard a voice from heaven again, speaking. What did it say? Go, take the little scroll [βιβλίον] that is open in the hand of the angel.

The voice from heaven is the command of God, who breathes into the heart of the church and orders her to receive from the open book that which the church is to preach before the future peace. For it seems to us that to accept the open book from the hand of the angel is to understand the truth of the law and the prophets, which has been made manifest in Christ. And for that reason it says that [the church] should take the open book, which is no longer, as above, the sealed [book]. “For Christ is the end of the law unto righteousness for everyone who believes.” Christ, who is the truth, wished then to be born from the earth, that is, from Mary, when “Righteousness looked down from heaven.” That is why I think that it is said, “I heard a voice from heaven speaking with me,” just as [Christ] himself said, “I am the Beginning who is also speaking to you.”

And the voice which I heard from heaven spoke to me again, etc. As the Lord reveals the mysteries of the future time, saying: For the kingdom of heaven is at hand (Matthew X), the Church is also admonished to take up the same book of preaching. Although these words can also be fittingly applied to John himself, who would return to preach after exile.

And the voice which I heard again speaking to me, and saying: Go, take the book from the hand of the angel who standeth upon the sea, and upon the earth. The voice that ordered him above to seal the voices of the thunders for those who would not believe them or for little people, is now inviting the holy Church, in its preachers, to the book open. This voice is understood to be a spiritual one with which God instructs the hearts of preachers so that they may understand the manifest truth of the law and the prophets, which is shut, whether in the seven thunders or in the seven seals, for those who are doomed to perish altogether. The steps with which the holy Church goes to the angel are not physical, but spiritual; they are the mental desire by which it is seen to come closer to God. Then since the voice of the angel giving this order is followed by a most ready state of mind on the saints' part, it is rightly said after that: