Commentaria in Isaiam
You will ask, why did the Seraph touch the lips of Isaias with this coal? I answer, that he might punish and expiate the sin of his lips, he therefore burned them with this coal; especially because Isaias had sinned by not rebuking Ozias, who had seized the coals and incense of the altar; he is punished, then, by coals; for this is what the Seraph says: “Behold this hath touched thy lips, and thy iniquity shall be taken away, and thy sin shall be cleansed.” This coal, therefore, is first a symbol of penance and contrition. Alcazar on Apocalypse 2:17, and Viegas on Apocalypse 8, Commentary 1, section 4, at the end, note that this coal was a carbuncle, as I have said. If anyone object: How could the fire of the altar be fed with carbuncles? The answer is that coals were put into the fire, but by the force of the fire were turned into carbuncles, to signify the power of our altar of holocaust, namely penance, by which sinners who were like coals, cold and black, come forth as carbuncles and gems, that is, they become either carbuncles by the ardour of charity, or emeralds by chastity, or diamonds by patience and fortitude; hence it is said in Psalm 17: “Coals were kindled by it,” and not only kindled, but by God’s power changed into gems. This speculation is more pious and subtle than sound: for carbuncles are not generated from coals, nor can fire change coals into carbuncles. But it could be answered that this vision (and what was seen), being symbolic, was not natural but miraculous and divine. So we read that St. Vincent Ferrer, when two criminals were being led to execution, by his exhortation so kindled them to sorrow that their faces became as if truly coals, and so they expired. Sorrow and love were therefore as it were their executioner, and the maker of new men.
Secondly, this burning coal was a symbol of the grace of the Holy Spirit, which purifies and sanctifies the soul of Isaias and of every penitent from sins. So St. Ambrose, On the Holy Spirit, book 1, chap. 9.
Thirdly, this coal was a symbol of grace freely given, namely of prophecy, as if to say: Behold, by this sign, namely an imaginary one (for this was a vision: hence all things were done by vision, not in reality; the lips of Isaias were not really burned: for thus he would have been made dull and unfit for preaching), by the touch of the lips with the coals God signifies that he both forgives your sins and fills you with the prophetic spirit, and at once with confidence and magnanimity, that, overcoming fear of the great, you may henceforth prophesy fearlessly, and reprove the blindness of the people and the nobles: hence St. Jerome, Haymo and Philastrius, in the book On Heresies, at the end, take by the coal the word of God, which is taken from the altar, that is, from sacred Scripture. So Jeremias was consecrated a Prophet by the touch of the divine hand, chap. 1. Hence St. Jerome, Dionysius the Carthusian, Sanchez and others hold that this was the first vision and prophecy of Isaias, and that those which have already been narrated in five chapters were later than this, and so Isaias, animated by this vision, thundered: “Hear the word of the Lord, ye princes of Sodom,” as was said in chap. 1. This opinion is probable; but the contrary seems truer: for that Isaias prophesied before this is gathered not only from the preceding chapters, but from the words “because I have held my peace!” as if to say: Woe to me, who, being a Prophet, ought not to have kept silent! as the Fathers and interpreters commonly expound. Secondly, because Eusebius in the Chronicle relates that Isaias began to prophesy in the 17th year of Ozias; and Isaias, chap. 1, says that he prophesied under King Ozias, that is, while he was reigning; therefore he prophesied before his death, indeed before he was struck with leprosy and set apart; for then he ceased to reign. Thirdly, because it is not likely that he began his prophecy thus: “Blind the heart of this people,” as he himself begins here, verse 10. For God is wont first to warn and rebuke the people through the Prophets, as he did through Isaias in the five preceding chapters, before he threatens them with blinding and hardening.
Fourthly, Isaias, wishing to join the Seraphim in the praise of God, was to be inflamed by this coal of their charity and ardour, and at the same time through it as it were consecrated not only Prophet but Evangelist and Apostle (for he is sent to the Jews, verse 9), just as the Apostles were consecrated by the fiery tongues which they received at Pentecost: with this coal, therefore, Isaias received a fiery mouth and a fiery tongue, equally with the Apostles, to inflame the Jews with divine fire, according to that of Jeremias 23: “Are not my words as a fire?” and Psalm 118: “Thy word is exceedingly fiery.” This burning coal therefore dedicates Isaias to the Gospel, so that nothing may sound from his mouth but what is pure, evangelical, divine; that his lips may breathe nothing but what is fiery from that heavenly fire which Christ came to send upon the earth. So St. Francis was inflamed by the Seraph with the coal of the love of God; for, as St. Bonaventure says, chap. 13 of his Life: “When, with Seraphic ardours of desire, he was being borne upward into God, about the feast of the Exaltation of the Holy Cross, while he prayed, he saw a Seraph with six fiery and shining wings descending from heaven, and between the wings appeared the likeness of a crucified man: two wings were raised above his head, two were stretched out for flight, and two veiled the whole body. Seeing this he was stupefied with joy: he understood at length from this, the Lord revealing it, that he was to be transformed wholly into the likeness of Christ crucified, not by martyrdom of the flesh, but by the fire of the mind. For this vision left a wonderful ardour in his heart, and impressed on his hands and feet the marks of the nails, as he had seen in that image of the crucified.”
Allegorically, this coal that inflames us is Christ; so St. Basil and Cyril: for as fire is united to the coal, and the coal to fire, so the humanity is united to the Word, that the incarnate Word is as it were a burning coal.
Again, this coal is the Holy Eucharist, which purges, strengthens and inflames us from every sin:
“That like lions breathing fire we may depart from that table, made terrible to the devil,” says St. Chrysostom, homily 61 to the people. So St. Justin expounds this coal in his Answer to Question 44, proposed by the Gentiles, and Damascene, who will soon be cited.
Hence morally a priest is here admonished, who ought to be pure and fervent as the Seraphim, to take the body of Christ in the Eucharist from the altar with tongs, which are two-pronged, that is, with faith and charity; or with the twofold perfection of the law, namely love of God and of neighbour, and to deliver it to Isaias, that is, to the penitent sinner who has confessed, laments, and approaches with reverence. St. Cyril explains this copiously, On the Incarnation of the Only-begotten, chap. 7.
Hear also St. Damascene, On the Faith, book 4, chap. 14: “Let us approach,” he says, “with ardent desire, forming our hands in the shape of a cross, let us receive the body of the Crucified, and setting our eyes and lips and forehead to it, let us take in the divine coal, that the fire of desire planted in us, taking to itself the kindling that arises from the coal, may burn up our sins, and enlighten our hearts, and that by participation in the divine fire we may be set aflame and deified. Isaias saw a coal; but a coal is not simple wood, but wood united to fire: so the bread of communion is not simple bread, but bread united to the divinity.” St. Monica experienced this, who in Holy Communion, for sweetness, could not contain herself from exulting, so that sighing to Christ she was lifted from the earth into the air and said: “My heart and my flesh have rejoiced in the living God.”
Lastly, Rupert applies this to the keys, and to the power of the keys given to Blessed Peter and his successors. For the Seraph is the priest, who by the coal of his sentence absolves Isaias, that is, the penitent, from sins.
Tropologically, St. Cyril understands by this coal applied to the mouth of Isaias confession, by which we profess the faith with the mouth as well as our sins: for this ought to be constant and unceasing in our mouth, that we may be cleansed from sins and kindled with the fervour of the Holy Spirit. Foolishly, therefore, Calvin says here that “in the Papacy is mere corruption, where the Sacraments are turned into a stage-play.” For by the same reasoning it follows that this Angel, who took the coal from the altar with tongs and touched and effectively purged the lips of Isaias, was a stage-actor. Let Calvin answer that the Angel added a word to his action, in which the chief nature of the Sacraments consists. But Catholics likewise use this word in their Sacraments. You know, Calvin, that saying of Augustine, Tract 80 on John: “The word is added to the element, and it becomes a Sacrament.” You know that Catholics give the nature of form to the words in the Sacraments: the form is indeed superior to the matter, and gives being to the thing, namely the Sacrament. But I know your ulcer: you want the word to be preaching, not consecrating: namely you wish to abolish the sacraments, and turn them into sermons. This is your mind, this your aim.
WHICH HE HAD TAKEN FROM THE ALTAR.—This altar was like the Mosaic one, and that which John saw, Apocalypse 6:9, and was either the altar of holocausts, or rather of incense, of which Apocalypse 8:3; for from it rose the smoke of incense with which the temple was filled. He mentions the altar because he saw God in the temple, whose ornament is the altar: for the altar represents the sacred secret of the divine Majesty, and the worship, religion and sacrifices due to him: for with these he is to be worshipped at the altar; and because coals were wont to be taken in the temple from the altar. What each altar signifies symbolically I have said on Exodus