After the Resurrection, the first day of the week was considered by the Apostles as the Lord’s Day, *dominica dies*^8, when He achieved for us, through His Resurrection, the victory over sin and death. For this reason, the early Christians held their liturgical meetings on Sunday. This has been the constant and universal tradition until our present day. "By an apostolic tradition which took its origin from the very day of Christ's resurrection, the Church celebrates the paschal mystery every eighth day; with good reason this, then, is called the Lord's Day or Sunday"^9.
This precept of sanctifying feast days regulates an essential duty of man toward his Creator and Redeemer. On this day dedicated to God, we worship Him especially through participation in the Sacrifice of the Mass. No other celebration could fulfill the meaning of this precept.
Alongside Sunday, the Church determined the feasts that commemorate the principal events of our salvation: Christmas, Easter, the Ascension, Pentecost, other feasts of the Lord, and the feasts of the Blessed Virgin. Along with these, from the beginning, Christians celebrated the *dies natalis* or the anniversary of the martyrdom of the first Christians. Christian feasts eventually even ordered the civil calendar itself. Following the calendar, the Church "commemorates the mysteries of redemption, she opens to the faithful the riches of her Lord's powers and merits, so that these are in some way made present for all time, and the faithful are enabled to lay hold upon them and become filled with saving grace"^10.
The center and origin of the joy of the Christian feast is found in the presence of the Lord in His Church, which is the pledge and anticipation of a definitive union in the feast that will have no end^11. Hence the joy that floods the Sunday celebration, as seen in the Prayer over the Offerings of today's Mass: *Receive, Lord, the offerings of your Church exulting with joy; and since in the resurrection of your Son you gave us reason for such great gladness, grant us to share in this eternal joy.* Therefore, our feasts are not a mere remembrance of past events, as the anniversary of a historical event might be, but rather a sign that manifests and makes Christ present among us.
The Holy Mass makes Jesus present in His Church and is a Sacrifice of infinite value offered to God the Father in the Holy Spirit. All other human, cultural, and social values of the feast must occupy a secondary place, each in its own order, without ever overshadowing or replacing what must be fundamental. Alongside the Holy Mass, manifestations of liturgical and popular piety have an important place, such as Eucharistic worship, processions, singing, greater care in dress, etc.
We must strive, through example and apostolate, for Sunday to be "the Lord's Day, the day of adoration and glorification of God, of the Holy Sacrifice, of prayer, of rest, of recollection, of the joyful gathering in the intimacy of the family"^12.
HCD