9 To this it must be added that by this same Sacrament our hope of everlasting blessedness, based on our trust in the divine assistance, is wonderfully strengthened. For the edge of that longing for happiness which is so deeply rooted in the hearts of all men from their birth is whetted even more and more by the experience of the deceitfulness of earthly goods, by the unjust violence of wicked men, and by all those other afflictions to which mind and body are subject. Now the venerable Sacrament of the Eucharist is both the source and the pledge of blessedness and of glory, and this, not for the soul alone, but for the body also. For it enriches the soul with an abundance of heavenly blessings, and fills it with a sweet joy which far surpasses man's hope and expectations; it sustains him in adversity, strengthens him in the spiritual combat, preserves him for life everlasting, and as a special provision for the journey accompanies him thither. And in the frail and perishable body that divine Host, which is the immortal Body of Christ, implants a principle of resurrection, a seed of immortality, which one day must germinate. That to this source man's soul and body will be indebted for both these boons has been the constant teaching of the Church, which has dutifully reaffirmed the affirmation of Christ: "He that eateth my flesh and drinketh my blood hath everlasting life; and I will raise him up at the last day" (St. John vi., 55).
Source: Mirae Caritatis (Vatican.va)