Introíbo ad altáre Dei

Sacerdos paratus cum ingreditur ad Altare, facta illi debita reverentia, signat se signo crucis a fronte ad pectus, et clara voce dicit:

The priest stands at the foot of the altar, makes the reverence due to it, and signs himself from forehead to breast. The first words of Mass are said aloud.

Deinde, iunctis manibus ante pectus, incipit Antiphonam:

With hands joined before his breast the priest begins the antiphon and the server answers. From here until he goes up to the altar the prayers alternate.