Last week, the Immaculate Conception fell on a Monday and the question was raised whether, in light of can. 1248 §1, one could satisfy both obligations by attending one Mass on Sunday evening. The canonist Dr. Peters put that question to rest rather thoroughly on his blog.
At the end of his post he made reference to a 1974 dubium to the Congregation of Clergy on the matter, which was included in the Bishops’ Committee on the Liturgy Newletter for that month. For completeness and in the hopes of putting this finally to rest especially for those who would like an authoritative statement on the matter, I post the text of the relevant part of that USCCB’s newsletter, as cited by Peters. Perhaps, at some point I’ll hunt down the original dubium if I can, but it wouldn’t change anything.
Fulfillment of Holyday and Sunday Mass Precept
In reply to inquiries it received, the Congregation for the Clergy clarified the matter of simultaneous fulfillment of holyday and Sunday obligations by attendance at the evening vigil mass.
By way of example the following dubium was presented: “Whether the faithful who attend Mass on Saturday, 15 August, would fulfill the double precept of hearing Mass on Saturday, feast of the Assumption, and Sunday, 16 August”?
The Congregation responded “Negative” to the above case and all analogous cases.
The indult by which the faculty is given to fulfill the obligation of attending Mass on the evening of a Saturday or of a feast day of obligation is generally granted in view of rendering easier the fulfillment of such a precept, without prejudice of keeping every Lord’s Day holy.
(BCL Newsletter vol. 10, n. 11 (Nov 1974); reprinted in USCCB, 35 Years of the BCL Newsletter, p. 450.)
One’s ability to fulfill the obligation to attend Mass on the preceding evening is now, obviously, a matter of law and not of indult, but the point of the last paragraph remains: the object is to make it easier to fulfill one’s obligations, not eliminate one’s obligations.