One of the most frustrating things in my life as a priest is taking part as a visitor in large Masses without a Master of Ceremonies. If an MC tells us where to process, bow and genuflect then the whole ceremony can be carried out with dignity. Without an MC it depends on priests having a shared knowledge of the liturgical rules and a respect for the dignity of the liturgy.
Few priests seem to realise than in the revised Roman Missal, in the absence of a deacon, a concelebrating priest should speak the invitation to the sign of peace and the dismissal. Of course, when I am the second and only other priest present with a principal celebrant, I never initiate this, because I can almost guarantee you he won’t expect it. (I have only once since 2011 had a presiding priest point at the relevant texts and expect me to say them!)
If I am the principal, without the assistance of a deacon, then in theory I am supposed to elevate the chalice myself. But to the concelebrant standing next to me, this will seem a rude and selfish gesture unless he has read the new rules and knows he is not meant to assist with the chalice at that moment.
For a principled Aspie, this is a terrible dilemma. I have made a promise to celebrate the liturgy according to the rules (liturgical law is an extension of canon law). But if I follow them I will sow discord. At least in this case there is a principle, which the Church has thoughtfully put in writing (GIRM 95 and 96), that you go with what makes for a harmonious display of unity even when that’s against the letter of the law. The rules apply more directly to being a member of the congregation (so if the majority stand when they should kneel, you should too, rather than implicitly rebuking your fellow worshippers by kneeling anyway).
As for processions, it’s rare that a group of more than a handful of priests will intuit the same ideas about where they should bow and genuflect on a given sanctuary. Hence the need for an MC.
In the Old Testament Book of Judges, we are given the story of Jephthah. In a fit of joy, he makes a rash promise that he will sacrifice to God the first living creatures he spies on his estate when he returns home. But when he is within sight of home his only daughter runs out to greet him – “Daddy, Daddy, you’re home!”
Jephthah faces an impossible choice – sacrifice his daughter or break a solemn vow to God. He decides to be a man of his word, though he allows his daughter some months to ‘bewail her virginity’ before sacrificing her. Here the Bible is clearly warning against rash vows rather than endorsing human sacrifices, but there is also a cautionary tale against forcing believers into vows which could backfire. The New Testament generally advises against the making of oaths (see e.g. James and Matthew).
At least there is some wriggle room in the liturgy to preserve harmony rather than the letter of the law, but I do dream of a day when all the priests at Mass have read the same Memo so we know what to do. The Book of Revelation describes Heaven as a liturgy – perhaps that’s so we priests can finally have a chance to get it right!