3. John, in the Prologue of his Gospel, captures in one phrase all the depth of the mystery of the Incarnation. He writes: "And the Word became flesh and dwelt among us, full of grace and truth; we have beheld his glory, glory as of the only Son from the Father" (1:14). For John, the Incarnation of the Eternal Word, of one being with the Father, took place in the conception and birth of Jesus. The Evangelist speaks of the Word who in the beginning was with God, and through whom everything which exists was made; the Word in whom was life, the life which was the light of men (cf. 1:1-4). Of the Only-Begotten Son, God from God, the Apostle Paul writes that he is "the first-born of all creation" (Col 1:15). God created the world through the Word. The Word is Eternal Wisdom; the Thought and Substantial Image of God; "He reflects the glory of God and bears the very stamp of his nature" (Heb 1:3). Eternally begotten and eternally loved by the Father, as God from God and Light from Light, he is the principle and archetype of everything created by God in time.

The fact that in the fullness of time the Eternal Word took on the condition of a creature gives a unique cosmic value to the event which took place in Bethlehem two thousand years ago. Thanks to the Word, the world of creatures appears as a "cosmos", an ordered universe. And it is the same Word who, by taking flesh, renews the cosmic order of creation. The Letter to the Ephesians speaks of the purpose which God had set forth in Christ, "as a plan for the fullness of time, to unite all things in him, things in heaven and things on earth" (1:9-10).