In principio ...

APERI, Dómine, os meum ad benedicéndum nomen sanctum tuum: munda quoque cor meum ab ómnibus vanis, pervérsis et aliénis cogitatiónibus; intelléctum illúmina, afféctum inflámma, ut digne, atténte ac devóte hoc Offícium recitáre váleam, et exaudíri mérear ante conspéctum divínæ Majestátis tuæ. Per Christum Dóminum nostrum. Amen.

Open thou, O Lord, my mouth to bless thy holy Name; cleanse also my heart from all vain, evil, and wandering thoughts; enlighten my understanding; enkindle my affections; that I may say this Office worthily, with attention and devotion, and so be meet to be heard in the presence of thy divine Majesty. Through Christ our Lord. Amen.