During Mass, the priest that presides is always reading from the book placed on the altar. Why is that? Shouldn’t he already know what is said at Mass? The book from which the priest reads is called the Roman Missal, which contains the structure and prayers that will be made during the Mass according to the liturgical season, as well as the Eucharistic prayers. This book also contains special indications for the celebrant called rubrics, where the rules according to which the liturgy is celebrated are indicated, they bear this name because they are written in red ink on the missal to distinguish them from the rest of the prayers.
The use of the missal is very important, since it means that Masses follow the same format in all the places where they are celebrated, thus forming a fundamental part of the unity and universality of the Church.
In the Roman Missal we can also find the General Instruction of the Roman Missal, which establishes the norms of how the Mass is to be celebrated, either with only the priest (GIRM 120-170), with the priest and a deacon (GIRM 171-186), or a concelebrated Mass (GIRM 199-251); what should be the order of the participants of the entrance procession (GIRM 120); at what times genuflection and bowing should be made (GIRM 274-275), what words should be said on certain occasions, for example, when distributing communion (GIRM 286-287).
Let us celebrate the Eucharistic sacrifice wherever we are, whether at home, visiting someone, or on vacation, for our Holy Mother Church has allowed us to feel at home every time we attend Mass, which we recognize by praying the Creed when we say the phrase “I believe in One, Holy, Catholic and Apostolic Church”