Instructions to the Double is a book about what Tess Gallagher calls the "true disguises" of the world, the way the world addresses us and what we see and hear instead. The poems are full of doubles: shadows, reflections in eyes and water and mirrors, resemblances ("Your neck, so / like hers", "each moon so like a moon"), photographs, a body's impression burnt onto bedsprings in a fire. These doubles attest to a hidden, static quality in what happens—its beauty really—as the real figures busy themselves with their lives….

Gallagher's people move and then like ghosts continue past their actions. They're seen in silhouette, or moving in slow motion, from a future they're unaware of. Some of them are still present in the places they have left or died in. They possess power over her that they never knew they had—and now over her readers.

She...