Pope Pius XII
Mystici Corporis Christi §48
Mystici Corporis Christi: On the Mystical Body of Christ
48 Christ must be acknowledged Head of the Church for this reason too, that, as supernatural gifts have their fullness and perfection in Him, it is of this fullness that His Mystical Body receives. It is pointed out by many of the Fathers, that as the head of our mortal body is the seat of all the senses, while the other parts of our organism have only the sense of touch, so all the powers that are found in Christian society, all the gifts, all the extraordinary graces, attain their utmost perfection in the Head, Christ. "In Him it hath well pleased the Father that all fulness should dwell." He is gifted with those supernatural powers that accompany the hypostatic union, since the Holy spirit dwells in Him with a fulness of grace than which no greater can be imagined. To Him has been given "power over all flesh"; "all the treasures of wisdom and knowledge are in Him" abundantly. The knowledge which is called "vision" He possesses with such clarity and comprehensiveness that it surpasses similar celestial knowledge found in all the saints of heaven. So full of grace and truth is He that of His inexhaustible fullness we have all received.
Source: Mystici Corporis Christi (Vatican.va)