. . . liturgy has its own structure, rhythm and pace:  a gathering, a building up, a climax, and a descent to dismissal.  It alternates between persons and groups of persons, between sound and silence, speech and song, movement and stillness, proclamation and reflection, word and action.  The art form must never see to interrupt, replace or bring the course of liturgy to a halt.  If one uses film, for example, in such a way that one seems to by saying, 'We will stop the liturgy for a few moments now in order to experience this art form,' then that use is inappropriate.  If, however, an art form is used to enhance, support and illumine a part of parts of the liturgical action or the whole action, it can be both appropriate and rewarding."

Environment and Art in Catholic Worship, #25