Cyril of Alexandria : Let our lips be touched by the divine coal, which burns away out sins and consumes the filth of our transgressions. Moreover, it makes us zealous by the Spirit. By saying "taken from the altar with tongs," Isaiah means that we receive faith in and knowledge of Christ from the teachings or announcements in the law and the prophets, in which the word of the holy apostles confirms the truth. By quoting from the law and the prophets, the apostles convince their hearers and "touch their lips with the burning coal" in order to lead them to confess faith in Christ. — COMMENTARY ON Isaiah 1:4 Gregory the Dialogist : But Dionysius the Areopagite, that ancient and venerable Father, is said to declare that from the lesser hosts of angels some are sent forth to fulfill their ministry either visibly or invisibly, namely because angels or archangels come for human consolation. For those higher hosts never withdraw from the inner places, since those who are preeminent have no function of external ministry. This seems to be contradicted by what Isaiah says: "And one of the Seraphim flew to me, and in his hand was a coal which he had taken with tongs from the altar, and he touched my mouth." But in this statement of the prophet, he wants it understood that the spirits who are sent receive the name of those whose office they perform. For the angel who carries a coal from the altar to burn up the sins of speech is called a Seraphim, which means burning. This interpretation is also believed to be supported not unsuitably by what is said through Daniel: "Thousands of thousands ministered to him, and ten thousand times a hundred thousand stood before him." For ministering is one thing, and standing before is another, because those minister to God who also go out to us announcing; but those stand before who so enjoy inward contemplation that they are not at all sent forth to accomplish external works. — Forty Gospel Homilies, Homily 34 Jerome : (Verse 6) And one of the Seraphim flew to me, and in his hand was a live coal which he had taken with tongs from the altar, and he touched my mouth, and said: Behold, this has touched your lips, and your iniquity shall be taken away, and your sin be cleansed. He flew, or rather, one of the Seraphim was sent, the name of which means burning, in order to cleanse the impure lips of the Prophet with a fiery coal which he had taken from the altar. However, many believe that there are two Seraphim, because one was calling to the other, even though each individual could call out to the others; and the Septuagint edition suggests that there were actually many, who were interpreted as Seraphim, standing around him. And if it were spoken about two things, they would not have spoken in a circle, but they would have spoken from both sides. And this applies to the multitude of angels, which is prepared for the ministry of God. But the Seraphim are called in the plural number, and in the singular, Seraph; just as the Cherubim are called Cherub. But as for the altar under which the souls of the martyrs are seen in heaven, John speaks of it in the Apocalypse (Rev. 6); and this stone, which is interpreted as 'LXX coals of fire,' that is, a carbuncle, may not signify coal or charcoal, as many think, but a carbuncular stone, which is called fiery because of its flame-like color. From this we understand that the altar of God is filled with carbuncles, that is, fiery stones and embers, which cleanse sins. Hence we read in the Scriptures about God: Coals were kindled by Him (Psalms 18:9). And it is said of the Lord Himself that He is a consuming fire. And the Savior in the Gospel says: I have come to cast fire upon the earth (Luke 12:49), to baptize in the Holy Spirit and fire. For the fire will test the quality of each one's work (1 Corinthians 3). And he who is to be saved will be saved as if he passed through fire. And it should be noted that to Jeremiah, to whom it was said: Before I formed you in the womb, I knew you, and before you were born, I sanctified you (Jeremiah 1:5), because he did not have unclean lips, but had only said: I do not know how to speak, because I am young, the Lord himself stretched out his hand, and touched his mouth, and said: Behold, I have put my words in your mouth. Moreover, to Isaiah who said, 'I am a man with unclean lips, and I dwell in the midst of a people with unclean lips,' the hand of God is not extended, but a Seraphim is sent by God, or flies of its own accord, because it is entrusted with this task. And in its hand it holds a coal, which according to the Septuagint and Theodotion, is grasped with tongs; according to Aquila and Symmachus, who have followed the Hebrew, with forceps it grasps, that is, 'he cleanses his iniquities,' so that it may touch his mouth and purify his ancient sins. However, it is the hand that is sent from God and the Seraphim, so that the Prophet, seeing a member of his own body, is not frightened by external touch. Some of our people consider the forceps, with which a stone is grasped, to be the two Testaments, which are united by the union of the Holy Spirit. But because the Lord is introduced as sitting, and sitting in the Temple, and the house is filled with smoke, as the Jews think, of incense; consequently, forceps are also mentioned, which we read about in the priestly ministry (Exodus 37). — Commentary on Isaiah John Damascene : With eyes, lips and faces turned toward it, let us receive the divine burning coal, so that the fire of the coal may be added to the desire within us to consume our sins and enlighten our hearts, and so that by this communion with the divine fire we may be set afire and deified. Isaiah saw a live coal, and this coal was not plain wood but wood joined with fire. Thus also, the bread of communion is not plain bread but bread joined with the Godhead. And the body joined with the Godhead is not one nature. On the contrary, that of the body is one, whereas that of the Godhead joined with it is another—so that both together are not one nature but two. — ORTHODOX FAITH 4:13