About suffering they were never wrong,
The Old Masters; how well they understood
Its human position; how it takes place
While someone else is eating or opening a window or just walking dully along;
How, when the aged are reverently, passionately waiting
For the miraculous birth, there always must be
Children who did not specially want it to happen, skating
On a pond at the edge of the wood:
They never forgot
That even the dreadful martyrdom must run its course
Anyhow in a corner, some untidy spot
Where the dogs go on with their doggy life and the torturer's horse
Scratches its innocent behind on a tree.
This refers to the martyrdom of Jesus, echoing the ‘miraculous birth’. 
 It may also allude to the debunking of what Auden called the ‘heroic ideal’ and his view that war was ‘dreadful’.  Note that he experienced soldiering at first hand in the front lines of the  Spanish Civil War and the Sino-Japanese War , and it coloured his view of life thereafter.
Musée des Beaux Arts