In the earnest and beautiful Travel Notes from the River Styx, Susanna Lang peers into the tiny mirrors of a river’s current, the mirror her father cannot see himself in, the rearview mirror in which she spies sandhill cranes on an afternoon drive as she interrogates the natural and, at times, unnatural world. The result is a collection of double images: the moon a “copper coin with the sheen worn off,” “the flag [that] slips down the pole,” the country where her grandmother was born once called Russia, now Ukraine. As clear in its language...