"Alzheimer's" by Jane Hirshfield.

When a fine, old carpet
is eaten by mice,
the colors and patterns
of what's left behind
do not change.
As bedrock, tilted,
stays bedrock,
its purple and red striations unbroken.
Unstrippable birthright grandeur.
How are you," I asked,
not knowing what to expect.
"Contrary to Keatsian joy," he replied.