III. When is the Liturgy Celebrated?

From The Catechism of the Catholic Church

1166
“By a tradition handed down from the apostles which took its origin from
the very day of Christ’s Resurrection, the Church celebrates the Paschal
mystery every seventh day, which day is appropriately called the Lord’s Day or
Sunday.”³⁶ The day of Christ’s Resurrection is both the first day
of the week, the memorial of the first day of creation, and the “eighth
day,” on which Christ after his “rest” on the great sabbath
inaugurates the “day that the Lord has made,” the “day that
knows no evening.”³⁷ The Lord’s Supper is its center, for there
the whole community of the faithful encounters the risen Lord who invites them
to his banquet:³⁸

PART TWO: THE CELEBRATION OF THE CHRISTIAN MYSTERY

SECTION ONE THE SACRAMENTAL ECONOMY
- CHAPTER TWO THE SACRAMENTAL CELEBRATION OF THE PASCHAL MYSTERY
  - Article 1 CELEBRATING THE CHURCH’S LITURGY
    - III. When is the Liturgy Celebrated?

From The Catechism of the Catholic Church – rosary.team