Gravity of the First Precept

Obligation of First Precept.—The first precept of the Church obliges under pain of grave sin, because it determines a necessary act of religion (2148), and experience shows that where the Sabbath is neglected the social, spiritual and physical interests of man are seriously harmed (see Denzinger, n. 1202). There is always hope for Catholics who attend Mass, whereas those who miss Mass soon become Catholics only in name. But since neglect of worship may be only slightly disrespectful, and since the end of the precept may be substantially obtained without complete fulfillment, a transgression may be only venial by reason of lightness of matter.

(a) Preceptive Part.—Grave matter is a part of the Mass that is notable on account of dignity (i.e., the essential and integral parts of the Mass, for example, the Consecration and Communion), or on account of its duration (i.e., a third of the whole Mass, e.g., from the beginning to the Offertory inclusively, from the beginning to the Gospel and from the Communion to the end, from the Preface to the Consecration, from the Consecration to the Agnus Dei, etc.). Hence, he who is culpably absent or asleep during a notable part of the Mass sins gravely, but he who is absent or asleep during an inconsiderable part of the Mass (e.g., one who arrives just at the Offertory or who leaves after the Communion) sins venially, unless he is so disposed that he does not care how much he misses.

(b) Prohibitive Part.—Grave matter is labor that is notable on account of its quality (e.g., forensic proceedings even for a brief space on Sunday would be a serious distraction and scandal), or its quantity (e.g., two and a half hours given to very exhausting manual work, such as digging a ditch, three hours given to less arduous labor, such as sowing). He who commands ten laborers to work an hour each on Sunday cooperates in ten venial sins (see 219), but he may be guilty of mortal sin on account of scandal.