If Sunday is the day of the Lord, it is also the day of Christ. Dies Christi, the topic of Chapter II, extends from this section to number 30. Subtitle: The Day of the Risen Lord and of the Gift of the Holy Spirit. So John Paul II draws Pentecost into his thinking.
Resurrection first, a very old tradition:
19. “We celebrate Sunday because of the venerable Resurrection of our Lord Jesus Christ, and we do so not only at Easter but also at each turning of the week”: so wrote Pope Innocent I at the beginning of the fifth century,(Ep. ad Decentium XXV, 4, 7: PL 20, 555) testifying to an already well established practice which had evolved from the early years after the Lord’s Resurrection. Saint Basil speaks of “holy Sunday, honoured by the Lord’s Resurrection, the first fruits of all the other days”;(Homiliae in Hexaemeron II, 8: SC 26, 184) and Saint Augustine calls Sunday “a sacrament of Easter”.(Cf. In Io. Ev. Tractatus XX, 20, 2: CCL 36, 203; Epist. 55, 2: CSEL 34, 170-171)
Sunday is a tradition shared between East and West:
The intimate bond between Sunday and the Resurrection of the Lord is strongly emphasized by all the Churches of East and West. In the tradition of the Eastern Churches in particular, every Sunday is the anastàsimos hemèra, the day of Resurrection,(The reference to the Resurrection is especially clear in Russian, which calls Sunday simply “Resurrection” (Voskresenie).) and this is why it stands at the heart of all worship.
If Creation began the reflection on Sunday, then as Christian we must ponder the Resurrection to give it its full modern meaning, at least to Christians:
In the light of this constant and universal tradition, it is clear that, although the Lord’s Day is rooted in the very work of creation and even more in the mystery of the biblical “rest” of God, it is nonetheless to the Resurrection of Christ that we must look in order to understand fully the Lord’s Day. This is what the Christian Sunday does, leading the faithful each week to ponder and live the event of Easter, true source of the world’s salvation.
Catholic Sensibility 