The phrase means canonical hours, and Auden has written a poem, set on Good Friday, for each of the seven offices of the monastic day.
What we know to be not possible,
Though time after time foretold
By wild hermits, by shaman and sybil
Gibbering in their trances,
Or revealed to a child in some chance rhyme
Like will and kill, comes to pass
Before we realize it: we are surprised
At the ease and speed of our deed
And uneasy: It is barely three,
Mid-afternoon, yet the blood
Of our sacrifice is already
Dry on the grass; we are not prepared
For silence so sudden and so soon;
The day is too hot, too bright, too still,
Too ever, the dead remains too nothing.
What shall we do till nightfall?
Just as I was about to post this item I learned that the BBC’s Radio 3 is featuring all seven poems at intervals throughout the day today. The poems are introduced by Rowan Williams, the Archbishop of Canterbury, and read by the actor Tom Durham. You can listen here.