As we know, the Holy Father's area of expertise is that of fundamental theology; as a matter of fact his own habilitationsschrift and his book Revelation and Tradition, co-authored with Fr Karl Rahner, found its mature expression in the Dogmatic Constitution on Divine Revelation, promulgated on 18 November 1965.
Not unlike the Arian heresy which still flourished at least until the sixth century despite the First Ecumenical Council, many Catholics still suffer from a profound misunderstanding on the nature of "Divine Revelation" despite the clear teaching of the Second Vatican Council and, more recently, the 2008 Synod of Bishops.
Recently I came across a posting at a Traditionalist website in which someone wrote "Dei Verbum--revealed in Sacred Scripture and Divine Tradition." Besides the obvious paucity of proper Latin grammar, our blogger perpetuates the blunder that then-Father Ratzinger fought so hard to suppress: that Revelation is something contemporaneously tangible. Of course Fr Ratzinger had in mind the "propositional model" of Revelation, but our blogger comes close to the position and perhaps even surpasses Protestantism in equating Revelation and Scripture by insisting that Tradition "reveals" Scripture!
Consider three starting-points. First, in the Gospel According to John, we read at the end of the Prologue, "No one has ever seen God; the only Son, who is in the bosom of the Father, he has made him known [exēgēsato]" (RSV). The NAB is perhaps better, "...has revealed him." A direct-equivalency translation might read, "the Son, who is in the bosom of the Father, has exegeted him." According to the Fourth Evangelist, then, Jesus Christ, or more to the point, the Incarnate Word (cf. Jn 1:14) has "revealed", "exegeted", or "made known" the Father. It was God, qua God incarnate, who reveals God, albeit in a human language because his audience was the human race (Jn 1:1).
Second, the narratives of the Transfiguration makes abundantly clear the superiority of Jesus Christ as the revealer of God. The premise of the Transfiguration is that the Incarnate Word, as Divine Revelation, supersedes the revelation of the Old Testament, personified by Moses (= "the Law") and Elijah (= "the Prophets") when the two figures disappear and only Jesus remains, to which the Father says "Listen to him!" (Mt 17:5, Mk 9:7, Lk 9:35). It is significant that in each of these narratives, the evangelists were careful to preserve the note that Jesus was found "alone" in reference to the Father's voice.
Third, at the beginning of the Letter to the Hebrews, the author compares the history of God's self-disclosure by contrasting how God once "spoke through the prophets" but now "he has spoken to us by a Son" (Heb 1:1, 2).
The Dogmatic Constitution on Divine Revelation, Dei verbum, makes it clear that it is the Incarnate Word who is the revealer of God, and that there will be nothing more revealed:
Then, after speaking in many and varied ways through the prophets, "now at last in these days God has spoken to us in His Son" (Heb. 1:1-2). For He sent His Son, the eternal Word, who enlightens all men, so that He might dwell among men and tell them of the innermost being of God (see John 1:1-18). Jesus Christ, therefore, the Word made flesh, was sent as "a man to men." He "speaks the words of God" (John 3;34), and completes the work of salvation which His Father gave Him to do (see John 5:36; John 17:4). To see Jesus is to see His Father (John 14:9). For this reason Jesus perfected revelation by fulfilling it through his whole work of making Himself present and manifesting Himself: through His words and deeds, His signs and wonders, but especially through His death and glorious resurrection from the dead and final sending of the Spirit of truth. Moreover He confirmed with divine testimony what revelation proclaimed, that God is with us to free us from the darkness of sin and death, and to raise us up to life eternal.
The Christian dispensation, therefore, as the new and definitive covenant, will never pass away and we now await no further new public revelation before the glorious manifestation of our Lord Jesus Christ (see 1 Tim. 6:14 and Tit. 2:13). (Dei verbum, 4).
To equate Scripture and Tradition with Divine Revelation, then, is to compromise the finality of Divine Revelation in Jesus Christ. The Incarnate Word reveals the Father, and none else. In the Incarnate Word, everything that can be said of God has been said. Pentecost was, as it were, the "period" at the end of the divine discourse that was the life of Jesus Christ. Accordingly, therefore, Scripture and Tradition cannot "reveal" the Word of God precisely because to "reveal the revealer" reduces the revealer to a forerunner. It would reduce Jesus Christ to a "precursor of Scripture and Tradition" and lower him to the rank of St John the Baptizer, who was the Forerunner of the Lord.
Coming back to the Synod of Bishops, we must ask, if the Incarnate Word is the revealer of the Father, why do we need Scripture and Tradition?
What has been "said" in Divine Revelation has been committed to the memory of the Church. We find a pointed expression of this in the charism of infallibility which Christ has entrusted to his Church. Scripture and Tradition, therefore, are "aids to memory" as they help us to remember the deposit of faith that has been handed onto the Church. Inasmuch as I might have a childhood memory buried under more recent ones and a perchance visit home to browse through old family albums helps me to "recover" what I had apparently forgotten, the Church has recourse to the Bible and Tradition as a method to evoke an article of faith in her vast repository of memories of her Founder. As the Synod Father said in their "Message to the People of God":
The Sacred Scriptures “bear witness” to the divine word in written form. They memorialize the creative and saving event of revelation by way of canonical, historical and literary means. Therefore, the word of God precedes and goes beyond the Bible which itself is “inspired by God” and contains the efficacious divine word (cf. 2 Tm 3:16). This is why our faith is not only centered on a book, but on a history of salvation and, as we will see, on a person, Jesus Christ, the Word of God made flesh, man and history. Precisely because the capacity of the divine word embraces and extends beyond the Scripture, the constant presence of the Holy Spirit that “will lead you to the complete truth” (Jn 16:13) is necessary for those who read the Bible. This is the great Tradition: the effective presence of the "Spirit of truth" in the Church, guardian of Sacred Scripture, which are authentically interpreted by the Church’s Magisterium. This Tradition enables the Church to understand, interpret, communicate and bear witness to the word of God. Saint Paul himself, proclaiming the first Christian creed, will recognize the need to “transmit” what he “had received” from Tradition (1 Cor 15:3-5). ("Message of the Synod of Bishops to the People of God," no. 3).
Scripture and Tradition, then, "bear witness" to the Incarnate Word who reveals the Father. Since it was born of the Church (for they were written by members of the Church, e.g. St Paul the Apostle) under unrepeatable circumstances (e.g. "inspiration"), it cannot supersede Divine Revelation but only testify to it. And because they are family albums, only members of the family called "Church" are entitled to insert themselves into its audience (cf. Tertullian, Praescriptione haereticorum, 15.3-4) and see themselves in the memories evoked. More importantly, the Church's "memory" of the Incarnate Word must be coupled with the fact that God has no memory but lives at each moment in history instantaneously. In the sacred liturgy, the mystery of anamnesis takes place in which the syntaxis is inserted into the event of Christ and therefore become contemporaneous with the life of the Incarnate Word, especially in his paschal mystery.
It is in the liturgy, then, that we "hear" the Father's Son, that we become participants in the act of Divine Revelation, beholding the Father in the face of Jesus Christ, this liturgy which bears Tradition and proclaims Scripture. It would be appropriate, here at the end of this posting, to include the great "Hymn of Justinian" chanted in the Byzantine Rite before the Liturgy of the Word. It captures well the subject-matter of our reflection:
Only-Begotten Son and immortal Word of God,
who for our salvation did will to become incarnate
of the holy Theotokos and Ever-Virgin Mary,
who without change did become Man and was crucified, O Christ our God,
trampling down death by death, who are one of the Holy Trinity,
glorified with the Father and the Holy Spirit, save us!