47. Even if in the earliest times it was not judged necessary to be prescriptive, the Church has not ceased to confirm this obligation of conscience, which rises from the inner need felt so strongly by the Christians of the first centuries. It was only later, faced with the half-heartedness or negligence of some, that the Church had to make explicit the duty to attend Sunday Mass: more often than not, this was done in the form of exhortation, but at times the Church had to resort to specific canonical precepts. This was the case in a number of local Councils from the fourth century onwards (as at the Council of Elvira of 300, which speaks not of an obligation but of penalties after three absences)(78) and most especially from the sixth century onwards (as at the Council of Agde in 506).(79) These decrees of local Councils led to a universal practice, the obligatory character of which was taken as something quite normal.(80)
The Code of Canon Law of 1917 for the first time gathered this tradition into a universal law.(81) The present Code reiterates this, saying that "on Sundays and other holy days of obligation the faithful are bound to attend Mass".(82) This legislation has normally been understood as entailing a grave obligation: this is the teaching of the Catechism of the Catholic Church,(83) and it is easy to understand why if we keep in mind how vital Sunday is for the Christian life.
(78) Cf. Canon 21, Mansi, Conc. II, 9.
(79) Cf. Canon 47, Mansi, Conc. VIII, 332.
(80) Cf. the contrary proposition, condemned by Innocent XI in 1679, concerning the moral obligation to keep the feast-day holy: DS 2152.
(81) Canon 1248: "Festis de praecepto diebus Missa audienda est": Canon 1247, 1: "Dies festi sub praecepto in universa Ecclesia sunt...omnes et singuli dies dominici".
(82) Code of Canon Law, Canon 1247; the Code of Canons of the Eastern Churches, Canon 881, 1, prescribes that "the Christian faithful are bound by the obligation to participate on Sundays and feast days in the Divine Liturgy or, according to the prescriptions or legitimate customs of their own Church sui iuris, in the celebration of the divine praises".
(83) No. 2181: "Those who deliberately fail in this obligation commit a grave sin".
