Apostolic Constitution of Pope Pius XII defining the dogma of the Assumption, 1 November 1950
That privilege [the Assumption] has shone forth in new radiance since our predecessor of immortal memory, Pius IX, solemnly proclaimed the dogma of the loving Mother of God's Immaculate Conception. These two privileges are most closely bound to one another. Christ overcame sin and death by his own death, and one who through Baptism has been born again in a supernatural way has conquered sin and death through the same Christ. Yet, according to the general rule, God does not will to grant to the just the full effect of the victory over death until the end of time has come. And so it is that the bodies of even the just are corrupted after death, and only on the last day will they be joined, each to its own glorious soul.
Now God has willed that the Blessed Virgin Mary should be exempted from this general rule. She, by an entirely unique privilege, completely overcame sin by her Immaculate Conception, and as a result she was not subject to the law of remaining in the corruption of the grave, and she did not have to wait until the end of time for the redemption of her body.
Thus, when it was solemnly proclaimed that Mary, the Virgin Mother of God, was from the very beginning free from the taint of original sin, the minds of the faithful were filled with a stronger hope that the day might soon come when the dogma of the Virgin Mary's bodily Assumption into heaven would also be defined by the Church's supreme teaching authority.
[Pope Pius goes on to give many proofs of the doctrine of the Assumption from the tradition of the Church, as well as some based on Scripture.]
All these proofs and considerations of the holy Fathers and the theologians are based upon the Sacred Writings as their ultimate foundation. These set the loving Mother of God as it were before our very eyes as most intimately joined to her divine Son and as always sharing his lot. Consequently it seems impossible to think of her, the one who conceived Christ, brought him forth, nursed him with her milk, held him in her arms, and clasped him to her breast, as being apart from him in body, even though not in soul, after this earthly life. Since our Redeemer is the Son of Mary, he could not do otherwise, as the perfect observer of God's law, than to honor, not only his eternal Father, but also his most beloved Mother. And, since it was within his power to grant her this great honor, to preserve her from the corruption of the tomb, we must believe that he really acted in this way.
We must remember especially that, since the second century, the Virgin Mary has been designated by the holy Fathers as the new Eve, who, although subject to the new Adam, is most intimately associated with him in that struggle against the infernal foe which, as foretold in the protoevangelium, would finally result in that most complete victory over the sin and death which are always mentioned together in the writings of the Apostle of the Gentiles. Consequently, just as the glorious resurrection of Christ was an essential part and the final sign of this victory, so that struggle which was common to the Blessed Virgin and her divine Son should be brought to a close by the glorification of her virginal body, for the same Apostle says: "When this mortal thing hath put on immortality, then shall come to pass the saying that is written: Death is swallowed up in victory."
Hence the revered Mother of God, from all eternity joined in a hidden way with Jesus Christ in one and the same decree of predestination, immaculate in her conception, a most perfect virgin in her divine motherhood, the noble associate of the divine Redeemer who has won a complete triumph over sin and its consequences, finally obtained, as the supreme culmination of her privileges, that she should be preserved free from the corruption of the tomb and that, like her own Son, having overcome death, she might be taken up body and soul to the glory of heaven where, as Queen, she sits in splendor at the right hand of her Son, the immortal King of the Ages.
After we have poured forth prayers of supplication again and again to God, and have invoked the light of the Spirit of Truth, for the glory of Almighty God who has lavished his special affection upon the Virgin Mary, for the honor of her Son, the immortal King of the Ages and the Victor over sin and death, for the increase of the glory of that same august Mother, and for the joy and exultation of the entire Church; by the authority of our Lord Jesus Christ, of the Blessed Apostles Peter and Paul, and by our own authority, we pronounce, declare, and define it to be a divinely revealed dogma: that the Immaculate Mother of God, the ever Virgin Mary, having completed the course of her earthly life, was assumed body and soul into heavenly glory.
Hence if anyone, which God forbid, should dare willfully to deny or to call into doubt that which we have defined, let him know that he has fallen away completely from the divine and Catholic Faith.
I, PIUS, Bishop of the Catholic Church, have signed, so defining.
Notes44. Gn 3:15.45. Rm 5-6; I Cor. 15:21-26, 54-57.46. I Cor 15:54.47. Bull Ineffabilis Deus, loc. cit., p. 599.
48. 1 Tm 1:17.
Excerpted from Pope Pius XII's Apostolic Constitution defining the dogma of the Assumption, Munificentissimus Deus, 1 November 1950