you turn the thing and make a choice about what you'd prefer to sacrifice

The old man eating walnuts knows the trick:
you do it wrong for many years,
applying pressure to the seams
to split the shell along its hemispheres.

It seems so clear and easy. There's the line.
You follow the instructions, then
your snack ends up quite pulverized.
You sweep your lap, and mutter, try again.

Eventually you learn to disbelieve
the testimony of your eyes.
You turn the thing and make a choice
about what you'd prefer to sacrifice.

You soon discover that the brains inside
are on right angles, so the shell
must be cracked open on its arc,
which isn't neat. The shattered pieces tell

a story, but the perfect, unmarred meat's
the truth: two lobes, conjoined, intact.
One of two things is bound to break:
One the fiction, one the soul, the fact.

[Jennifer Keith, 'Eating Walnuts', from The Best American Poetry, 2015]