5. The fullest synthesis of this truth is contained in the Prologue of the Fourth Gospel. It can be said that in that text the truth about the divine pre-existence of the Son of Man acquires a further, in a certain sense definitive explication: "In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God: all things were made through him . . . In him was life, and the life was the light of men; the light shines in the darkness, but the darkness did not receive it" (Jn 1:1-5).
In these phrases the evangelist confirms what Jesus said of himself when he declared: "I came forth from the Father and have come into the world" (Jn 16:28), or when he prayed that the Father would glorify him with that glory that he had taken of him before the world was (cf. Jn 17:5). At the same time, the pre-existence of the Son in the Father is closely connected with the revelation of the Trinitarian mystery of God: the Son is the eternal Word, he is "God from God", of the same substance as the Father (as the Council of Nicaea expressed it in the Symbol of Faith). The Council formula precisely reflects John's Prologue: "The Word was with God and the Word was God". Affirming the pre-existence of Christ in the Father is tantamount to recognising his Divinity. To his substance, as to the substance of the Father, belongs eternity. This is what is indicated by the reference to the eternal pre-existence in the Father.
6. John's Prologue, through the revelation of the truth about the Word contained therein, constitutes as it were the definitive completion of what the Old Testament had already said about Wisdom. See, for example, the following statements: "Before the ages, from the beginning he created me; for all eternity I shall not fail" (Sir 24:9), "My creator pitched my tent and said to me: pitch your tent in Jacob" (Sir 24:8). Wisdom, of whom the Old Testament speaks, is a creature and at the same time has attributes that place her above the whole of creation: "Though unique, she can do all things; though remaining in herself, she renews all things" (Wis 7:27).
The truth about the Word, contained in John's Prologue, reconfirms in a certain sense the revelation about wisdom in the Old Testament, and at the same time transcends it in a definitive way. The Word not only "is with God", but "is God". Coming into this world in the person of Jesus Christ, the Word "came among his own people", for "the world was made through him" (cf. Jn 1:10-11). He came among "his own" because he is "the true light, the one who enlightens every man" (cf. Jn 1:9). The self-revelation of God in Jesus Christ consists in this "coming" into the world of the Word, who is the eternal Son.
7. "The Word became flesh and dwelt among us; and we beheld his glory, glory as of the only begotten of the Father, full of grace and truth" (Jn 1:14). Let us say it once again: John's Prologue is the eternal echo of the words with which Jesus says: "I came forth from the Father and have come into the world" (Jn 16:28), and of those with which he prays that the Father will glorify him with that glory that he had with him before the world was (cf. Jn 17:5). The Evangelist has before his eyes the Old Testament revelation about Wisdom, and at the same time the entire Paschal event: the departure through the cross and the resurrection, in which the truth about Christ, Son of Man and true God, became completely clear to those who were his eyewitnesses.
[Pope John Paul II, General Audience 2 September 1987]
