III. When is the Liturgy Celebrated?

From The Catechism of the Catholic Church

1171
In the liturgical year the various aspects of the one Paschal mystery unfold.
This is also the case with the cycle of feasts surrounding the mystery of the
incarnation (Annunciation, Christmas, Epiphany). They commemorate the beginning
of our salvation and communicate to us the first fruits of the Paschal mystery.

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