The Father is the Unknowable and Ineffable Creator of all things, the first principle and that hypostasis which is the Unbegotten Begetter of the Son. The Father is said to be “unknowable” in apophatic theology, not because the Father is somehow non-existent in a strict sense, nor because he is too far above us that he so chooses to be unknowable, but because his fullness can never be described. He is without qualities in this respect, not because he is lacking, but because we are.
The Son is the eternally begotten Self-emanation of the Father, the exact Image of the Father, and the means through which the Father becomes knowable. The Son perfectly demonstrates the nature of the Father to be known by his creations, and shows that his unknowability without the Son is due to our limited intellect, not of any fault or lacking in the Divine. In cataphatic thelogy, where God is described positively rather than negatively, it is God as revealed through the Son that is described. The Son is a distinct hypostasis from the Father, though finding his being in the Father as one who from the Father was manifested from eternity to eternity.
The nature of God to act proceeds from the Father through the Son as the Holy Spirit, a personal and distinct hypostasis from both. We call the Holy Spirit the Holy Spirit because it proceeds from both the Father and the Son, where both the Father and the Son are Spirit and are Holy. The best name we can give the Spirit is Love, for it is by the Spirit that the Father loves the Son, by the Spirit that the Son loves the Father, and by the Spirit that both love the world.
Thus, it is by the Love that is the Spirit that the Father became known to the world in the Son, the Son having assumed unto himself the human nature of “Jesus of Nazareth”, who is called the Christ by virtue of appointment by God. From the being of the Christ, the Divine Person of the Son speaks, and within the being of Christ are both the human nature of body and soul and the Divine Nature shared by the hypostases of the Trinity. Thus, Paul saw it fitting to declare, “In him, the fullness of the Godhead dwelt bodily”, and “in him was the fullness of God pleased to dwell”
It should be remembered that the incarnation of the Son in Jesus of Nazareth does not in any way limit the ability of the Son, or any other Divine Person, to incarnate through the assumption of one or more additional human natures; thus, we cannot strictly define incarnation, as one of the above has done, by the assumption of the human nature into the Divine Personality of the Son in the being of Jesus of Nazareth. We must only define the incarnation as the assumption of any human nature by any member of the Trinity at any time. Though the West knows the incarnation of God chiefly through Jesus, it must be conceded, as was by Saint Thomas Aquinas, that the Son may incarnate in any and all human natures, as the potency of the Uncreated cannot be diminished by what is created, namely, the human nature of the Christ.
