Private intepretation is not in the vocabulary of St. Augustine, hence St. Augustine is foreign to the formal aspect of Sola Scriptura. The testimonies from St. Augustine are legion affirming that Scripture, Tradition and Church are inseparable as opposed to Sola Scriptura (i.e.Bible and one's private interpretation to obtain the truth). The words of St. Augustine in his work dealing with the Manichean heresy: 'For in the Catholic Church, not to speak of the purest wisdom, to the
knowledge of which a few spiritual men attain in this life, so as to know it, in the scantiest measure, indeed, becuase they are but men, still without any uncertainty...The consent of peoples and nations keep me in Church, so does her authority, inaugerated by miracles, nourished by hope, enlarged by love, established by age. The SUCCESSION of priests keeps me, beginning from the very seat of the APOSTLE PETER, to whom the Lord, after his resurrection, gave it in charge to feed his sheep, down to the present EPISCOPATE...The epistle begins thus:--`Manicheus, an apostle of Jesus Christ, by the providence of God the Father. These are the wholesome words from the perennial and living fountain.` Now, if you please, patiently give heed to my inquiry. I do not believe Manichues to be an apostle of Christ. Do not, I beg you, be enraged and begin to curse. For you know that it is
my rule to believe none of your statements without consideration. Therefore I ask, who is this Manicheus? You will reply, An Apostle of Christ. I do not believe it. Now you are at a loss what to say or do; for you promised to give knowledge of truth, and here you are forcing me to believe what I have no knowledge of. Perhaps you will read the gospel to me, and will attempt to find there a testimony to Manicheus.But should you meet with a person not yet beleiving in the gospel, how would you reply to him were he to say, I do not believe? For MY PART, I should NOT BELEIVE the gospel except moved by the authority of the Catholic Church. So when those on whose authority I have consented to beleive in the gospel tell me not to beleive in Manicheus, how can I BUT CONSENT?'
Likewise we have Augustine affirming the need for interpreting Scripture in light of Tradition/Church and never apart from them:
"Wherever this tradition comes from, we must believe that the Church has not believed in vain, even though the express authority of the canonical scriptures is not brought forward for it" Letter 164 to Evodius of Uzalis
"To be sure, although on this matter, we cannot quote a clear example taken from the canonical Scriptures, at any rate, on this question, we are following the true thought of Scriptures when we observe what has appeared good to the universal Church which the authority of these same Scriptures recommends to you"
C. Cresconius I:33
"It is obvious; the faith allows it; the Catholic Church approves; it is true" Sermon 117:6
"Will you, then, so love your error, into which you have fallen through adolescent overconfidence and human weakness, that you will separate yourself from these leaders of Catholic unity and truth, from so many different parts of the world who are in agreement among themselves on so important a question, one in which the essence of the Christian religion involved..?" C. Julian 1:7,34
Like the rest of the Fathers who intepreted the Scriptures in light of Tradition and Church, Augustine affirmed Catholic doctrines such as the real presence:
'For Christ was carried in his own hands when, entrusting to us his own Body,
he said: "This is my Body." Indeed he was carrying that Body in his own hands'
Ennar. In Ps 33
The farthest thing from Augustine, like the rest of the Fathers, is that he interprets Scripture within the milieu of tradition and Church as opposed to private interpretation.
Similarly, St. Augustine affirms the authority of Tradition (via the monument of universal belief and usage) regarding prayers for the dead. We read:
"In the books of Maccabees we read of sacrifice offered for the dead. Howbeit, even if their were no where at all read in the Old Scriptures, not small is the authority, which in this usage is clear, of the whole Church, namely that in the prayers of the priest which are offered to the Lord God at His altar, the commendation of the death hath its place"
De Cura Pro Mortuis I,3
Likewise, St. Augustine appeals to Tradition and Church regarding the doctrine of infant baptism. In this passage we find St. Augustine affirm a couple of aspects of Tradition; 1)viewed as a belief held by the whole Church , 2) a belief that is entrenched in antiquity and 3)a belief that is unchanging. In addition, we find St. Augustine contrasting the apostolic authority of invariable custom with the authority placed in the Church (in Council)...Again we find St. Augustine, like Athanasius and the rest of the
Fathers, upholding Church, Scripture and Tradition as opposed to the Scriptures Alone.
And this is the firm tradition of the universal church, in respect of baptism of infants...and if one seek for divine authority in this matter, though what is held by the WHOLE Church, and that not as instituted by Councils, but as a matter of invariable custom, is rightly held to have been handed down by APOSTOLIC authority..." ibid IV,31
For St. Augustine, Scripture is the criterion of faith but not at the exclusion of tradition and Church. That is why St. Augustine explicitly affirms (eg. heretical baptism, infant baptism etc.) what the Church has traditionally/generally held to be of apostolic authority. In addition, St. Augustine also affirms that this tradition is entrusted to the Church and preserved by apostolic succession. Regarding infant baptism and original sin St. Augustine affirms that his interpretation was in-line with the
traditional teaching of the Church and not his private interpretation he writes:
For who does not see in what degree Coelestius was bound by the interrogations of your holy predecessor and by the answers of Coelestius, whereby he professed that he consented to the letters of Pope Innocent, and fastened by a most wholesome chain, so as not to dare any further to maintain that the original sin of infants is not put away in baptism? Because these are the words of the venerable Bishop Innocent concerning this matter to the Carthaginian Council....'by the purification of a new
regeneration, purged all past sin by the washing of baptism.' What could be more clear than the judgement of the Apostolic See?"