might be able to see what was going on through the open door.
5. It is necessary to have the intention of hearing Mass, and it must be done with the requisite attention. The Church prescribes a human action to be performed in the service of God, and so there must be the necessary constituents of a human act. The act, then, must be voluntary; there must be the wish or the intention to hear Mass. So that one who was forced to be present against his will, or who came to church merely as a companion to another, or to hear the music, would not hear Mass.
Attention is an act of the mind by which we advert to what is going on. This is attention in the proper sense of the term, and is called internal to distinguish it from external attention, which is the avoidance of any external action which is incompatible with internal attention. Thus if one is distracted during Mass and thinking of other things, but does no external action which is incompatible with hearing Mass, he has external, but not internal attention. If during Mass he engages in a prolonged conversation with a neighbour, or reads a profane book, or paints, he has not even external attention.
The Church commands at least external attention while Mass is being said, otherwise the precept will not be fulfilled. All, too, admit that voluntary distractions during Mass are venially sinful, just as they are during ordinary prayer. It is a disputed point among theologians whether internal attention is also necessary for the observance of the Church's law. The more common opinion holds that it is. The contrary, however, is probable, for actual attention does not seem to be an essential element of prayer; the form of Extreme Unction, which is a prayer, is certainly valid even if said by a priest without internal attention. The Church's law, therefore, which directly provides for external decorum in the service of God, would seem to be fulfilled, provided that there is at least external attention while hearing Mass. This opinion does not foster the careless hearing of Mass, but it does serve to relieve the scrupulous conscience from needless anxieties.
6. We have here to do with a positive precept, and any serious inconvenience or loss, spiritual or temporal, affecting one's self or one's neighbour, which would follow from hearing Mass, will excuse the faithful from fulfilling the obligation.
