Adaptation by Ada Limon

Adaptation

It was, for a time, a loud twittering flight
of psychedelic-colored canaries: a cloud
of startle and get-out in the ornamental
irons of the rib cage. Nights when the moon
was wide like the great eye of a universal
beast coming close for a kill, it was a cave
of bitten bones and snake skins, eggshell dust,
and charred scraps of a frozen-over flame.
All the things it has been: kitchen knife
and the ancient carp's frown, cavern of rust
and worms in the airless tire swing,
cactus barb, cut-down tree, dead cat
in the plastic crate. Still, how the great middle
ticker marched on, and from all its four chambers
to all its forgiveness, unlocked the sternum's
door, reversed and reshaped until it was a new
bright carnal species, more accustomed to grief,
and ecstatic at the sight of you.

by Ada Limon

I love how this poem piles together a series of elaborate and starling metaphors for the heart. The range of metaphors recreates the range of things we feel in our hearts: colorful flutter of birds, an empty cave, knife, fish frown, cave filled with rust and worms, cut-down tree, dead cat in a plastic crate. The heart feels all of these things! The poem plays on the medical term of adaptation... hearts adapt to different conditions, get stronger, more able to pump oxygen. In this poem it becomes "a new/bright carnal species" that is both "accustomed to grief" and, at the same time, "ecstatic at the sight of you."