That determines the law with respect to how Mass is celebrated. It doesn’t change the fact that a Saturday vigil Mass fulfills the Sunday obligation, even if the Saturday vigil Mass is a TLM.
About Saturday vigils however, I question how a 4:00 PM Mass can be said to fulfill the Sunday obligation, since historically, the new day began at sundown and the Sun is never down at 4:00 PM (well with exception of extreme latitudes in the Winter).
I think I can help you here. I don’t know how it happened, but I do know what happened. Until the Council of Trent, the liturgical life of the Western Church was driven by religious orders. Secular priests followed along, with all due respect to them. At some point the secular clergy and laity went on their own and the religious orders continued to do what we had always done.
In religious houses of men, to this day, Sunday begins with Vespers on Saturday. Vespers is celebrated between 4:30 – 6:00 pm. That’s where the Church gets its tradition. It’s really a reconciliation between the secular and the monastic or as I say it, getting everyone back on the same page. Because Roman Catholicism is highly European, that’s how the 4:30 time comes into play. Long before the existence of electricity, sunset in winter was around 4:30 and religious houses were very dark. You celebrated Vespers at dusk, while you still had some light. Once you celebrated Vespers, you could not go back to the liturgy of Saturday. You have to move forward. This is still the rule. For example, people who pray the Office of Readings instead of Matins, will pray the Office of Readings for Sunday after Vespers on Saturday, because liturgically, it’s Sunday.
Along the same line, the mass that is celebrated Saturday night is not a vigil mass or an anticipated mass. It is the Sunday mass. Those terms were incorrectly applied in the USA. The readings and collects are the same. Therefore, you can celebrate either the OF or the EF on Saturday evening. A vigil mass is different from the mass of the day. The readings, collects and even rubrics for a vigil mass are different from that of the day, observe the Easter Vigil and Midnight Mass at Christmas. However, the Church allows you to fulfill your Easter Sunday obligation and Christmas Day obligations with the Vigil mass for obvious reasons.
This has nothing to do with what you said, but I’ll just throw it in here. The EF has nothing to do with Canon Law, the Council or the CCC. People who choose to attend the EF exclusively, are still bound by the Code of Canon Law of 1983, must still use the CCC as the authoritative catechism of the Catholic Church and must comply with whatever is required by Vatican II. We don’t have two Latin Churches. There is only one Latin Church. Only the Easetrn Catholics are allowed to have their own Code of Canon Law.
Fraternally,
Br. JR, OSF
