39 Furthermore, the sacrament of Baptism—as St. Leo rightly claims—makes those who are washed in the sacred font not only members of Christ, but also sharers in His kingship and His priesthood. "All those who are reborn in Christ, the sign of the cross makes kings; the Holy Spirit's anointing consecrates them priests." (32) Confirmation, called by St. Leo "sanctification by chrism," (33) strengthens their assimilation to Jesus Christ, the Head of His body, the Church, and the sacrament of the Eucharist perfects this union. "For," as St. Leo says, "the reception of Christ's Body and Blood does nothing less than transform us into that which we consume, and henceforth we bear in soul and body Him in whose fellowship we died, were buried, and are risen again." (34)
Source: Aeterna Dei Sapientia (Vatican.va)