(I will go in), the word taken from the 5th verse of the 42nd Psalm (in the Vulgate), with which the Roman Catholic priest, at the foot of the altar, after having made the sign of the cross, begins the mass, and to which the servitor replies with the rest of the verse. The whole psalm is then recited alternately by the priest and the servitor. In masses for the dead, and during Passion-week, the psalm is not pronounced.