What We Keep in Loss: William Blake’s Stirring Letter to a Bereaved Father

“Our deceased friends are more really with us than when they were apparent to our mortal part.”

“Each that we lose takes part of us / a crescent still abides, / which like the moon, some turbid night, / is summoned by the tides,” Emily Dickinson wrote as she reckoned with loss after her mother’s death a century and a half before neuroscience illuminated that abiding crescent as a synaptic reality engrained in the brain’s model of the world.

As the poet Meghan O’Rourke wrote in her own stunning...