From the 17th December leading up towards Christmas, the church prays what are known as the O Antiphons in vespers (evening prayer of the Church). The first letters of these ancient titles in Latin form an acrostic which is 'Ero cras', meaning 'Tomorrow, I will be [there]', The first letter of each title – Emmanuel, Rex, Oriens, Clavis, Radix, Adonai, Sapientia. the names given to the coming saviour.