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.

from W. H. Auden – Musée des Beaux Arts on Rap Genius

Meaning

This innocent behind may be a reference to another one of Breughel’s paintings, “The Slaughter of the Innocents.” You can see various horses and dogs chilling (and maybe even enjoying themselves) as the torturers get busy doing what they do.

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