CCC 1193
Christian Mystery›SECTION ONE THE SACRAMENTAL ECONOMY›CHAPTER TWO THE SACRAMENTAL CELEBRATION OF THE PASCHAL MYSTERY›IN BRIEF
Sunday, the "Lord's Day," is the principal day for the celebration of the Eucharist because it is the day of the Resurrection. It is the pre-eminent day of the liturgical assembly, the day of the Christian family, and the day of joy and rest from work. Sunday is "the foundation and kernel of the whole liturgical year" (SC 106).