“Observe” he says, “that we are instructed, in presenting the cup, to maintain the custom handed down to us from the Lord, and to do nothing that our Lord has not first done for us: so that the cup which is offered in remembrance of Him should be mixed with wine.”
But the Bible doesn’t say a thing about whether there should be water mixed with the wine in the Chalice. So it’s clear that St. Cyprian is appealing to Sacred Tradition here, rather than the Bible.
Nor can it be held that His blood, by which we are redeemed and vivified, is in the chalice when it contains no wine, through which the blood of Christ is shown, as is foretold by all the mysteries and testimonies of the Scriptures. [Ibid., quoted from the Robertson translation]
If Christ’s blood is not in the Cup when there is no wine (as Cyprian affirms), then it must be the case that Christ’s blood is in it when the wine is there.
Later (paragraph 47), St. Augustine quotes St. Cyprian again, this time concerning virgins:
Now our discourse addresses itself to the virgins, who, as they are the objects of higher honor, are also the objects of greater care. These are the flowers on the tree of the Church, the glory and ornament of spiritual grace, the joy of honor and praise, a work unbroken and unblemished, the image of God answering to the holiness of the Lord, the brighter portion of the flock of Christ. The glorious fruitfulness of their mother the Church rejoices in them, and in them flourishes more abundantly; and in proportion as bright virginity adds to her numbers, in the same proportion does the mother’s joy increase. And at another place in the end of the epistle, ‘As we have borne,’ he says, ‘the image of the earthly, we shall also bear the image of the heavenly.’ Virginity bears this image, integrity bears it, holiness and truth bear it; they bear it who are mindful of the chastening of the Lord, who observe justice and piety, who are strong in faith, humble in fear, steadfast in the endurance of suffering, meek in the endurance of injury, ready to pity, of one mind and of one heart in brotherly peace. And every one of these things ought ye, holy virgins, to observe, to cherish, and fulfill, who having hearts at leisure for God and for Christ, and having chosen the greater and better part, lead and point the way to the Lord, to whom you have pledged your vows. You who are advanced in age, exercise control over the younger. You who are younger, wait upon the elders, and encourage your equals; stir up one another by mutual exhortations; provoke one another to glory by emulous examples of virtue; endure bravely, advance in spirituality, finish your course with joy; only be mindful of us when your virginity shall begin to reap its reward of honor.
And similarly in paragraph 48, St. Ambrose (Augustine’s father in the Faith):
Ambrose also uses the temperate and ornamented style when he is holding up before virgins who have made their profession a model for their imitation, and says: “She was a virgin not in body only, but also in mind; not mingling the purity of her affection with any dross of hypocrisy; serious in speech; prudent in disposition; sparing of words; delighting in study; not placing her confidence in uncertain riches, but in the prayer of the poor; diligent in labor; reverent in word; accustomed to look to God, not man, as the guide of her conscience; injuring no one, wishing well to all; dutiful to her elders, not envious of her equals; avoiding boastfulness, following reason, loving virtue. When did she wound her parents even by a look? When did she quarrel with her neighbors? When did she spurn the humble, laugh at the weak, or shun the indigent? She is accustomed to visit only those haunts of men that pity would not blush for, nor modesty pass by. There is nothing haughty in her eyes, nothing bold in her words, nothing wanton in her gestures: her bearing is not voluptuous, nor her gait too free, nor her voice petulant; so that her outward appearance is an image of her mind, and a picture of purity. For a good house ought to be known for such at the very threshold, and show at the very entrance that there is no dark recess within, as the light of a lamp set inside sheds its radiance on the outside. Why need I detail her sparingness in food, her superabundance in duty,— the one falling beneath the demands of nature, the other rising above its powers? The latter has no intervals of intermission, the former doubles the days by fasting; and when the desire for refreshment does arise, it is satisfied with food such as will support life, but not minister to appetite.” Now I have cited these latter passages as examples of the temperate style, because their purpose is not to induce those who have not yet devoted themselves to take the vows of virginity, but to show of what character those who have taken vows ought to be. To prevail on any one to take a step of such a nature and of so great importance, requires that the mind should be excited and set on fire by the majestic style. Cyprian the martyr, however, did not write about the duty of taking up the profession of virginity, but about the dress and deportment of virgins. Yet that great bishop urges them to their duty even in these respects by the power of a majestic eloquence.
We may safely infer Augustine’s agreement with these authorities when he says—without a hint of disapprobation—“have cited these latter passages as examples of the temperate style, because their purpose is not to induce those who have not yet devoted themselves to take the vows of virginity, but to show of what character those who have taken vows ought to be.” But if this is insufficient, he goes even further in paragraph 50:
Now in these two authors whom I have selected as specimens of the rest, and in other ecclesiastical writers who both speak the truth and speak it well—speak it, that is, judiciously, pointedly, and with beauty and power of expression—many examples may be found of the three styles of speech, scattered through their various writings and discourses; and the diligent student may by assiduous reading, intermingled with practice on his own part, become thoroughly imbued with them all. [Emphasis added]
So we see that St. Augustine’s judgment is that St. Cyprian and St. Ambrose speak the truth in the passages that he has quoted from them concerning the Eucharist and concerning consecrated virginity. But these are Catholic views, not Protestant. So once again we see that St. Augustine was a Catholic.