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
The short line gives emphasis. The painters saw their task to reveal truths, to provide a moral commentary on humanity. 
 The technique of varying short and long lines gives shape and variation to the verse, creating interest in the long, discursive lines, and resolving suspense in the short, snappy ones. Most of all, short lines encapsulate meaning that impacts on the reader.
Musée des Beaux Arts