According to Catholic Christian teaching, the supernatural end of the redeemed is the beatific vision of God whereby the blessed will see the very essence of God. Mankind is not naturally able to attain so great of a goal and so the intellect is supernaturally perfected by what theologians call the lumen gloriae or "the light of glory".
Saint Thomas Aquinas explains that the beatific transcends man's natural powers:
The beatific vision and knowledge are to some extent above the nature of the rational soul, inasmuch as it cannot reach it of its own strength; but in another way it is in accordance with its nature, inasmuch as it is capable of it by nature, having been made to the likeness of God, as stated above. But the uncreated knowledge is in every way above the nature of the human soul (Summa theologiae IIIa q. 9, a. 2, ad 3).The doctrine is based on the passage in Paul: "We see now in a glass darkly, but then face to face" (1 Cor. 13:12) among others (cf. 1 Timothy 6:16; Matthew 5:8; Psalm 17:15).
The definition of the beatific vision was dogmatized at the the Council of Vienne in 1311 (Denz., n. 475; old, n. 403). The elect move from nature to grace to glory. Saint Paul spoke of this final glorification when he wrote: "And those whom he predestined he also called; and those whom he called he also justified; and those whom he justified he also glorified" (Rom 8:30).
Oddly enough, (the Avignon) Pope John XXII (1316 - 1334) privately held the heretical notion that the beatific vision could only be enjoyed by the saints after the Second Coming of Christ. Even the William Ockham opposed him in this. Apparently John XXII backed off of this toward the end of his pontificate. The Church teaches that the saints in Heaven currently enjoy the beatific vision.