966 "Finally the Immaculate Virgin, preserved free from all stain of original sin, when the course of her earthly life was finished, was taken up body and soul into heavenly glory, and exalted by the Lord as Queen over all things, so that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death." The Assumption of the Blessed Virgin is a singular participation in her Son's Resurrection and an anticipation of the resurrection of other Christians: In giving birth you kept your virginity; in your Dormition you did not leave the world, O Mother of God, but were joined to the source of Life. You conceived the living God and, by your prayers, will deliver our souls from death.
2853 Victory over the "prince of this world" was won once for all at the Hour when Jesus freely gave himself up to death to give us his life. This is the judgment of this world, and the prince of this world is "cast out." "He pursued the woman" but had no hold on her: the new Eve, "full of grace" of the Holy Spirit, is preserved from sin and the corruption of death (the Immaculate Conception and the Assumption of the Most Holy Mother of God, Mary, ever virgin). "Then the dragon was angry with the woman, and went off to make war on the rest of her offspring." Therefore the Spirit and the Church pray: "Come, Lord Jesus," since his coming will deliver us from the Evil One.
2177 The Sunday celebration of the Lord's Day and his Eucharist is at the heart of the Church's life. "Sunday is the day on which the paschal mystery is celebrated in light of the apostolic tradition and is to be observed as the foremost holy day of obligation in the universal Church."
"Also to be observed are the day of the Nativity of Our Lord Jesus Christ, the Epiphany, the Ascension of Christ, the feast of the Body and Blood of Christi, the feast of Mary the Mother of God, her Immaculate Conception, her Assumption, the feast of Saint Joseph, the feast of the Apostles Saints Peter and Paul, and the feast of All Saints."
The Assumption - Catechism of the Catholic Church