I've also included other examples of Augustine's usage, from discussion of other "sacraments," such as chrismation. Surely no one thinks that the water of baptism or the oil in chrismation is transubstantiated, yet you will see similar discussion of them.
1. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine, The Manichean Debate, Part 1, Vol. 19, trans. Boniface Ramsey, Answer to Adimantus, a Disciple of Mani, 12, §3 (Hyde Park: New City Press, 2006), p. 192.
For from the words of scripture that the blood of an animal is its soul, apart from what I said above, namely, that it is no concern of mine what happens to the soul of an animal, I can also interpret that commandment as a sign that was given. After all, the Lord did not hesitate to say, This is my body (Mt 26:26), when he gave us a sign of his body.
2. NPNF1-03, On the Trinity, Book 3, Chapter 10, Sections 20-21
20. But because these things are known to men, in that they are done by men, they may well meet with reverence as being holy things, but they cannot cause wonder as being miracles. And therefore those things which are done by angels are the more wonderful to us, in that they are more difficult and more known; but they are known and easy to them as being their own actions. An angel speaks in the person of God to man, saying, “I am the God of Abraham, and the God of Isaac, and the God of Jacob;” the Scripture having said just before, “The angel of the Lord appeared to him.” [Ex. iii. 6, 2] And a man also speaks in the person of God, saying, “Hear, O my people, and I will testify unto thee, O Israel: I am the Lord thy God.” [Ps. lxxxi. 8, 10] A rod was taken to serve as a sign, and was changed into a serpent by angelical power; [Ex. vii. 10] but although that power is wanting to man, yet a stone was taken also by man for a similar sign. [Gen. xxviii. 18] There is a wide difference between the deed of the angel and the deed of the man. The former is both to be wondered at and to be understood, the latter only to be understood. That which is understood from both, is perhaps one and the same; but those things from which it is understood, are different. Just as if the name of God were written both in gold and in ink; the former would be the more precious, the latter the more worthless; yet that which is signified in both is one and the same. And although the serpent that came from Moses’ rod signified the same thing as Jacob’s stone, yet Jacob’s stone signified something better than did the serpents of the magicians. For as the anointing of the stone signified Christ in the flesh, in which He was anointed with the oil of gladness above His fellows; [Ps. xlv. 7] so the rod of Moses, turned into a serpent, signified Christ Himself made obedient unto death, even the death of the cross. [Phil. ii. 9] Whence it is said, “And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up, that whosoever believeth in Him should not perish, but have everlasting life;” [John iii. 14, 15] just as by gazing on that serpent which was lifted up in the wilderness, they did not perish by the bites of the serpents. For “our old man is crucified with Him, that the body of sin might be destroyed.” [Rom. vi. 6] For by the serpent death is understood, which was wrought by the serpent in paradise, [Gen. iii] the mode of speech expressing the effect by the efficient. Therefore the rod passed into the serpent, Christ into death; and the serpent again into the rod, whole Christ with His body into the resurrection; which body is the Church; [Col. i. 24] and this shall be in the end of time, signified by the tail, which Moses held, in order that it might return into a rod. [Ex. iv. 4] But the serpents of the magicians, like those who are dead in the world, unless by believing in Christ they shall have been as it were swallowed up by, [Ex. vii. 12] and have entered into, His body, will not be able to rise again in Him. Jacob’s stone, therefore, as I said, signified something better than did the serpents of the magicians; yet the deed of the magicians was much more wonderful. But these things in this way are no hindrance to the understanding of the matter; just as if the name of a man were written in gold, and that of God in ink.
21. What man, again, knows how the angels made or took those clouds and fires in order to signify the message they were bearing, even if we supposed that the Lord or the Holy Spirit was manifested in those corporeal forms? Just as infants do not know of that which is placed upon the altar and consumed after the performance of the holy celebration, whence or in what manner it is made, or whence it is taken for religious use. And if they were never to learn from their own experience or that of others, and never to see that species of thing except during the celebration of the sacrament, when it is being offered and given; and if it were told them by the most weighty authority whose body and blood it is; they will believe nothing else, except that the Lord absolutely appeared in this form to the eyes of mortals, and that that liquid actually flowed from the piercing of a side [John xix. 34] which resembled this.
3. NPNF1-08, Expositions on the Psalms, Psalm 3, Section 1
And in the history of the New Testament by that so great and so wonderful forbearance of our Lord; in that He bore so long with him as if good, when He was not ignorant of his thoughts; in that He admitted him to the Supper in which He committed and delivered to His disciples the figure of His Body and Blood; finally, in that He received the kiss of peace at the very time of His betrayal; it is easily understood how Christ showed peace to His betrayer, although he was laid waste by the intestine war of so abominable a device. And therefore is Absalom called “father’s peace,” because his father had the peace, which he had not.
4. NPNF1-03, Of the Formal Admission of the Catechumen, Chapter 26, Section 50 (note that the sacrament he's discussing is probably not the Lord's Supper, but note that his comments are general and helpful in illustrating what Augustine means by "sign" and the like)
On the subject of the sacrament, indeed, which he receives, it is first to be well impressed upon his notice that the signs of divine things are, it is true, things visible, but that the invisible things themselves are also honored in them, and that that species, in reference to the outward and sensible sign of the salt, which is then sanctified by the blessing, is therefore not to be regarded merely in the way in which it is regarded in any common use. And thereafter he ought to be told what is also signified by the form of words to which he has listened, and what in him is seasoned by that (spiritual grace) of which this material substance presents the emblem. Next we should take occasion by that ceremony to admonish him that, if he hears anything even in the Scriptures which may carry a carnal sound, he should, even although he fails to understand it, nevertheless believe that something spiritual is signified thereby, which bears upon holiness of character and the future life. Moreover, in this way he learns briefly that, whatever he may hear in the canonical books of such a kind as to make him unable to refer it to the love of eternity, and of truth, and of sanctity, and to the love of our neighbor, he should believe that to have been spoken or done with a figurative significance; and that, consequently, he should endeavor to understand it in such a manner as to refer it to that twofold (duty of) love.
5a. Sermon 227 (Works of Saint Augustine, A Translation for the 21st Century: New City Press)
So they are great sacraments and signs, really serious and important sacraments. Do you want to know how their seriousness is impressed on us? The apostle says, Whoever eats the body of Christ or drinks the blood of the Lord unworthily is guilty of the body and blood of the Lord (1 Cor 11:27). What is receiving unworthily? Receiving with contempt, receiving with derision. Don't let yourselves think that what you can see is of no account. What you can see passes away, but the invisible reality signified does not pass away, but remains. Look, it's received, it's eaten, it's consumed. Is the body of Christ consumed, is the Church of Christ consumed, are the members of Christ consumed? Perish the thought! Here they are being purified, there they will be crowned with the victor's laurels. So what is signified will remain eternally, although the thing that signifies it seems to pass away. So receive the sacrament in such a way that you think about yourselves, that you retain unity in your hearts, that you always fix your hearts up above. Don't let your hope be placed on earth, but in heaven. Let your faith be firm in God, let it be acceptable to God. Because what you don't see now, but believe, you are going to see there, where you will have joy without end.
5b. (Alternative Translation) Trans. by Sr. Mary Sarah Muldowney, R.S.M., Sermons on the Liturgical Seasons, Sermon 227 (CUA Press, 2008) pp. 197-98.
Then, after the consecration of the Holy Sacrifice of God, because He wished us also to be His sacrifice, a fact which was made clear when the Holy Sacrifice was first instituted, and because that Sacrifice is a sign of what we are, behold, when the Sacrifice is finished, we say the Lord's Prayer which you have received and recited. After this, the 'Peace be with you' is said, and the Christians embrace one another with the holy kiss. This is a sign of peace; as the lips indicate, let peace be made in your conscience, that is, when your lips draw near to those of your brother, do not let your heart withdraw from his. Hence, these are great and powerful sacraments. Do you wish to know how they are commended? The Apostle says: 'Whoever eats the body of Christ or drinks the cup of the Lord unworthily, will be guilty of the body and blood of the Lord.' What does it mean to receive unworthily? To receive in mockery, to receive in contempt. Let the Sacrament not appear of trifling value to you because you look upon it. What you see passes; but the invisible, that which is not seen, does not pass; it remains. Behold, it is received; it is eaten; it is consumed. Is the body of Christ consumed? Is the Church of Christ consumed? Are the members of Christ consumed? God forbid! Here they are cleansed; there they will be crowned. Therefore, what is signified will last eternally, even though it seems to pass. Receive, then, so that you may ponder, so that you may possess unity in your heart, so that you may always lift up your heart. Let your hope be, not on earth, but in heaven; let your faith be firm and acceptable to God. Because you now believe what you do not see, you are going to see there where you will rejoice eternally.
6. NPNF1, Letter 98 (to Boniface), section 9
For if sacraments had not some points of real resemblance to the things of which they are the sacraments, they would not be sacraments at all. In most cases, moreover, they do in virtue of this likeness bear the names of the realities which they resemble. As, therefore, in a certain manner the sacrament of Christ’s body is Christ’s body, and the sacrament of Christ’s blood is Christ’s blood, in the same manner the sacrament of faith is faith. Now believing is nothing else than having faith; and accordingly, when, on behalf of an infant as yet incapable of exercising faith, the answer is given that he believes, this answer means that he has faith because of the sacrament of faith, and in like manner the answer is made that he turns himself to God because of the sacrament of conversion, since the answer itself belongs to the celebration of the sacrament. Thus the apostle says, in regard to this sacrament of Baptism: “We are buried with Christ by baptism into death.” [Rom. vi. 4.] He does not say, “We have signified our being buried with Him,” but “We have been buried with Him.” He has therefore given to the sacrament pertaining to so great a transaction no other name than the word describing the transaction itself.
7. NPNF1-2, On Christian Doctrine, Book 2, Chapter 1 (this is provided simply as Augustine's own explanation of what he means by signs)
As when I was writing about things, I introduced the subject with a warning against attending to anything but what they are in themselves, even though they are signs of something else, so now, when I come in its turn to discuss the subject of signs, I lay down this direction, not to attend to what they are in themselves, but to the fact that they are signs, that is, to what they signify. For a sign is a thing which, over and above the impression it makes on the senses, causes something else to come into the mind as a consequence of itself: as when we see a footprint, we conclude that an animal whose footprint this is has passed by; and when we see smoke, we know that there is fire beneath; and when we hear the voice of a living man, we think of the feeling in his mind; and when the trumpet sounds, soldiers know that they are to advance or retreat, or do whatever else the state of the battle requires.
8. NPNF1-2, On Christian Doctrine, Book 2, Chapter 3
Our Lord, it is true, gave a sign through the odor of the ointment which was poured out upon His feet; [John xii. 3–7; Mark xiv. 8.] and in the sacrament of His body and blood He signified His will through the sense of taste; and when by touching the hem of His garment the woman was made whole, the act was not wanting in significance.
9. NPNF1-04, On Baptism against the Donatists, Book 4, Chapter 10, Section 15
Nor is the water "profane and adulterous" over which the name of God is invoked, even though it be invoked by profane and adulterous persons; because neither the creature itself of water, nor the name invoked, is adulterous. But the baptism of Christ, consecrated by the words of the gospel, is necessarily holy, however polluted and unclean its ministers may be; because its inherent sanctity cannot be polluted, and the divine excellence abides in its sacrament, whether to the salvation of those who use it aright, or to the destruction of those who use it wrong. Would you indeed maintain that, while the light of the sun or of a candle, diffused through unclean places, contracts no foulness in itself therefrom, yet the baptism of Christ can be defiled by the sins of any man, whatsoever he may be? For if we turn our thoughts to the visible materials themselves, which are to us the medium of the sacraments, every one must know that they admit of corruption. But if we think on that which they convey to us, who can fail to see that it is incorruptible, however much the men through whose ministry it is conveyed are either being rewarded or punished for the character of their lives?
10. Trans. by Sr. Mary Sarah Muldowney, R.S.M., Sermons on the Liturgical Seasons, Sermon 213, Section 8 (CUA Press, 2008), pp. 128-29.
'I believe in the forgiveness of sins.' If this power were not in the Church, there would be no hope; if there were no remission of sins in the Church, there would be no hope of future life and of eternal salvation. We give thanks to God who gave this gift to His Church. Behold, you are about to come to the sacred font; you will be washed in baptism; you will be renewed in the saving laver of regeneration; when you rise from these waters, you will be without sin. All the sins which in the past haunted you will be wiped out. Your sins will be like the Egyptians following the Israelites, pursuing only up to the Red Sea. What does 'up to the Red Sea' mean? Up to the font consecrated by the cross and blood of Christ. For, because that font is red, it reddens. Do you not see how the member of Christ becomes red? Question the eyes of faith. If you see the cross, see the blood, too. If you see what hangs on the cross, see what drips down from it. The side of Christ was pierced with a lance and our purchase price flowed forth. Therefore, baptism is signified by the sign of Christ, that is, by the water in which you are immersed and through which you pass, as it were, in the Red Sea. Your sins are your enemies. They follow you, but only to the Red Sea. When you have entered [the water], you will escape; they will be destroyed, just as the Egyptians were engulfed by the waters while the Israelites escaped on dry land. And why does Scripture say: 'There was not one of them left'? Because, whether you have committed many or few, great or small sins, even the smallest of them has not remained. But, since we are destined to live in the world where no one lives without sin, on that account the remission of sin depends, not solely on the washing in holy baptism, but also on the Lord's daily prayer which you will receive after eight days. In that prayer you will find, as it were, your daily baptism, so that you may give thanks to God who has given to His Church this gift which we acknowledge in the Creed. Hence, when we have said: 'I believe in the holy Church,' let us add, 'and in the remission of sins.'
11. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine, Exposition of the Psalms, Part 3, Vol. 16, trans. Maria Boulding, O.S.B., Exposition of Psalm 44, §19 (Hyde Park: New City Press, 2000), p. 297:
Who, then, is the God who was anointed by God? Let the Jews tell us that. After all, these scriptures are theirs as well as ours. God was anointed by Go, and when you hear the word, "anointed," understand that it means Christ, for "Christ" is derived from "chrism," and the name "Christ" means "Anointed one." Nowhere else were kings and priests anointed; it was done only in that kingdom where Christ's coming was prophesied, where he was anointed, and from where the name Christ was to come. Nowhere else at all do we find this, in any other nation or kingdom. So God was anointed by God, and with what kind of oil? Spiritual, obviously. Visible oil is a sign; invisible oil is a sacramental mystery, for the spiritual oil is within. God was anointed for us, and sent to us. He was God, but he became man so that he could be anointed; yet he was man in such wise that he was God, and he was God in such a way that he did not disdain to be man. He is true man and true God, and there is no falsehood in him, for he is in every respect true, in every respect the very Truth. God became man, and it can be said that "God was anointed," because God became man, became Christ the Anointed One.
12. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine, Exposition of the Psalms, Part 3, Vol. 16, trans. Maria Boulding, O.S.B., Exposition 2 of Psalm 33 (Hyde Park: New City Press, 2000), p. 33:
The psalmist wants to speak openly now about the sacrament that the Lord held in his hands. Taste and see how sweet the Lord is. The psalm is opening its meaning to you know, surely? It shows you that the feigned insanity and persistent madness of David was a sane insanity, a sober intoxication, for he was prefiguring something. Like King Achis the Jews replied, "How can this be?" when the Lord kept telling them, Unless you eat my flesh and drink my blood, you will not have life in you (Jn 6:54). King Achis, who stands for error and ignorance, was sovereign in them as they objected, How can this man give us his flesh to eat? (Jn. 6:53). If you do not know, taste and see how sweet the Lord is; but if you do not understand this, you are King Achis. David will alter his behavior and withdraw from you; he will forsake you and go away.
13. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine Part 3, Vol. 10, trans. Edmund Hill, O.P., Sermons (341-400) on Various Subjects, Sermon 352, §4 (Hyde Park: New City Press, 1995), pp. 141-42:
And when Moses entrusted him with the task of bringing the people in, he summoned him, and changed his name, and called him Jesus; so that the people of God would enter the promised land not under Moses but under Jesus, that is to say, not under the law but under grace. But just as that man wasn't the true Jesus, but a model one, so too that promised land wasn't the real one, but a model one. It was a temporary one, you see, for the first people; whereas the one that has been promised to us will be eternal. But eternal realities were being promised and foretold under temporal, time-bound, models and symbols. So just as he wasn't the real Jesus, and neither was that the real promised land, but the model or symbol of it; so too that rock wasn't really Christ, but only symbolically, and so with all the other things.
14. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine Part 3, Vol. 7, trans. Edmund Hill, O.P., Sermons (230 - 272B) on Liturgical Seasons, Sermon 260A, §3 (Hyde Park: New City Press, 1993), p. 187.
So now they should stop saying to us, "What is there for you to give us, if we already have baptism?" They are so unaware of what they are saying, you see, that they are not even willing to read what holy scripture assures us of: that right inside the Church itself, that is to say, in the communion of the members of Christ, many were baptized in Samaria, and did not receive the Holy Spirit, but remained only in the baptismal state, until the apostles came to them from Jerusalem; while on the other hand Cornelius and those who were with him were found worthy to receive the Holy Spirit even before they received the sacrament of baptism. In this way God has taught us that the sign of salvation is one thing, salvation itself another; the form of godliness one thing, the power of godliness another.
15. John E. Rotelle, O.S.A., ed., The Works of Saint Augustine Part 3, Vol. 7, trans. Edmund Hill, O.P., Sermons (230 - 272B) on Liturgical Seasons, Sermon 232, §7 (Hyde Park: New City Press, 1993), p. 28.
And now then, my dearest friends, we have recognized the sacrament. Listen. He was walking with them, he is hospitably entertained, he breaks bread, and he's recognized. And we too must not say that we have not known Christ. We have known him if we believe. It's too little to say we have known him if we believe; we have him with us if we believe. They had Christ with them at a meal together; we have him inside in our spirits. It's a greater thing to have Christ in your heart than in your house. Our hearts, after all, are more inwardly attached to us than our houses. So now then, where ought the faithful to recognize him? The faithful know where; the catechumens, though, don't know; but nobody is shutting the door in their faces, to stop them knowing.
Perhaps that last one could better have gone in the previous section on the presence of Christ, but I thought it makes sense to include it here, as an example of the link between the issue of it being only a sacrament and the presence of Christ being a spiritual, inward presence.