Revelation 10:2

"I saw another mighty angel coming down from heaven, clothed with a cloud; and a rainbow was upon his head, and his face was as it were the sun, and his feet as pillars of fire: and he had in his hand an open book: and he set his right foot upon the sea, and his left foot upon the earth." He signifies that that mighty angel who, he says, descended from heaven, clothed with a cloud, is our Lord, as we have above narrated.

"His face was as it were the sun." That is, with respect to the resurrection.

"Upon his head was a rainbow." He points to the judgment which is executed by Him, of shall be.

"An open book." A revelation of works in the future judgment, or the Apocalypse which John received.

"His feet," as we have said above, are the apostles. For that both things in sea and land are trodden under foot by Him, signifies that all things are placed under His feet. Moreover, he calls Him an angel, that is, a messenger, to wit, of the Father; for He is called the Messenger of great counsel. He says also that He cried with a loud voice. The great voice is to tell the words of the Omnipotent God of heaven to men, and to bear witness that after penitence is closed there will be no hope subsequently.

With reason did his face shine "as the sun in full strength," for he opened the book that had been sealed in mystery. "He placed his right foot upon the sea and his left foot upon the land," so that he might confirm the precept of his law by land and by sea. Nor was it without reason that he placed his right foot on the sea and his left foot on the land. In the right foot he signifies the stronger members who have been made firm through great dangers. In the left foot he indicates the crowd of candidates who have not yet received the sign of the faith.

And he is said to have held in his hand a tiny open scroll [βιβλιδάριον]. Daniel, recalling such small scrolls [βιβλίων], says: "before him sat a judge, and scrolls [βίβλοι] were opened." (Dan. 7:10) The tiny scroll [βιβλιδάριον] was one in which were recorded the names and the multitude of the very impious who were to be punished. Therefore, it was also diminutively called a "tiny scroll" [βιβλιδάριον], since it is a kind of scroll [βίβλου]. Both terms have been used in the Holy Scripture, in which the names of all men are written, according to what was previously stated by me. The term "tiny scroll" [βιβλιδάριον] refers to the record containing the names of the exceedingly impious. For the worshippers of idols were not so numerous, nor marked by murders and poisonings and other afflictions that would serve to fill an entire scroll small [βιβλίον] with the diseases they caused.

And he set his right foot upon the sea, and his left foot on the land. This was a sign both of the greatness of the saints and a sign that those who have sinned on the earth as well as those in the sea, such as shipwrecked individuals or others who have committed evil deeds, would bear the consequences of punishment.

If earlier the deep secrets of the Old Testament were recognized to have been hidden in the sealed book, it is appropriate that the revealed grace of the New Testament is believed to be disclosed here in the opened book. Therefore, the apostle confidently says, "And we, with unveiled face, beholding the glory of the Lord, are being changed into his likeness from glory to glory, as though by the Spirit of the Lord." Indeed, this is why his face is said to shine like the sun. Moreover, the right foot upon the sea represents those members who are strong so that they might suffer the attacks of persecution.… The left foot upon the land represents those who are not exposed to the greater dangers. For God does not allow us to be tempted beyond what we are able, but with temptation [he] provides also a way, so that we might endure. It is certain, nonetheless, that the proclamation is extended by way of land and sea.

And he had in his hand a little book open. This is the book previously mentioned, which, long closed by its cover, was finally opened by the grace of the Lord, so that, according to the prophet, even the deaf might hear the words of the book (Isaiah XXIX). And his face deservedly shines like the sun, because he now carries the book open.

And he set his right foot on the sea, and his left foot on the land. The preaching of the Christian faith is spread by land and sea. But, allegorically, stronger members are set in greater dangers, and others in suitable places. For God does not allow us to be tempted beyond what we can bear (1 Corinthians X).

And he had in his hand a little book open. The angel's hand is the working of our salvation, that is Christ's incarnation. The little book open is the declared grace of the New Testament. Note also that if the angel's face had not shone first, he would not be holding the little book open in his hand, because it is in his plan that the whole sum of the Scriptures was revealed. And he set his right foot upon the sea, and his left foot upon the earth. In this sentence, a distinction is shown between preachers and between times: those who are, as it were, the right foot, are the stronger ones who are neither lifted up by success nor thrown down by adversity, and say, The darkness thereof, and the light thereof are alike. [Ps. 138:12] These are set upon the sea, that is, to endure the persecutions of the wicked. As for the left foot, it is those of lesser strength: as they are sent in time of peace, it is as if they were set upon the solidity of the earth. For just as a king sends his stronger men to face the enemy, so does Christ.