What is a Common Mass?
Never heard of it. Is it some take on “low” Mass?
It simply means that there are Mass texts that are available for saints days (or other occasions) that do not have their own very specific texts.
The best way to explain it is by example.
Let’s say that there is a Saint Whatshisname who was a martyr in the 2nd century. There is no specific set of Mass prayers for that saint. Since he is a martyr, the priest turns to the page for “Common for a martyr” and uses those prayers.
In the place that would usually have the saint’s actual name, there’s a fill-in-the-blank where the priest inserts the appropriate name (sometimes). For example “We pray for the intercession of St. (insert name) who gave his life for the Gospel…” The same prayer is used on different days for different saints because all of them are martyrs.
Same idea applies to other kinds of saints like bishops, pastors, consecrated religious, missionaries, etc.
Not every saint has specific Mass prayers that speak about the unique life of that saint, so the “commons” use generic statements that talk about types of saints instead.
FrDavid96, Thank you for the excellent answer!!