Article — Prümmer, Manuale Theologiae Moralis
Article I. On the Time of Celebrating Mass
¶40.
The time of celebration is determined by ecclesiastical law both as regards the days and as regards the hours. It is indeed lawful to celebrate Mass daily, but by Latin ecclesiastical law private Masses are prohibited on the last three days of Holy Week. On the other hand, several Masses are sometimes also permitted to be said on one day. For the sake of clarity, it is useful to treat separately: 1. Masses during the last three days of Holy Week; 2. several Masses to be said on the same day; 3. the hour at which Mass is to be celebrated.