Natasha Trethewey during book signing at the University of Michigan in 2011.

Natasha Trethewey during book signing at the University of Michigan in 2011.

Just over 53 years ago, a bomb exploded at the Sixteenth Street Baptist Church in Birmingham, Alabama. The predominately African-American congregation was preparing for Sunday service.

Four girls -- Addie Mae Collins, Denise McNair, Carole Robertson and Cynthia Wesley -- were killed. Many other people were hurt.

The bombing served as the inspiration for Pulitzer Prize-winning poet Natasha Trethewey's poem, "We Have Seen." The former U.S. Poet Laureate is director of Emory University's creative writing program.

The poem is published in the new issue of Smithsonian Magazine devoted to the National Museum of African American History and Culture

Former U.S. Poet Laureate and Pulitzer Prize winner Natasha Trethewey reads her poem, "We Have Seen."

We Have Seen: View from the window of the Sixteenth Street Baptist Church, September 15, 1963

Because they must have wanted the symbol

of their gospel visible to all, not only

to those inside the sanctuary, and perhaps

to show that the savior watches over them

both in and out of church, the congregation

chose the painting, not on canvas, but

stained glass: Christ the Good Shepherd

in a window facing east. In the aftermath

you could have seen, from a hole in the window,

what a photographer captured: a sign

on the building across the street, the word

"Liberty," its brutal irony in 1963, or

the dark windows two stories above

the shattered body of a car, the street

strewn with debris, the slick helmets of police

catching the sun -- how it all seems

crowded together, a flat perspective.

In the short depth of field, everything

is compressed into the ruined tableau.

If you could look beyond it –

the palimpsest of wreckage -- you might see

what should have been: a street scene

in which the parked fire truck is moving

through the grainy light, headed elsewhere;

the few onlookers, framed in the windows,

leaning out as if only to catch a breath

of air; the men on the street below them

going about the business of the day as if

it were any other; and in the middle ground,

a man raising a camera to capture

something we might have never had reason

to see. Instead his lens must find

the wounded church, the mangled remains

of windows, the twisted armatures –

rosettes dangling from each gnarled grasp. And,

as if to remind us of the angels, how

they might walk, unknown, among us,

as if to remind us of the martyred girls --

like Addie Mae Collins, her face no longer a face

her sister could recognize -- Jesus

too, the window, his body left nearly intact

but faceless, after the blast