The poem is just two short lines, and the whole meaning turns on one small change. The first line states something as fact: we see through these bodies. The second repeats it almost word for word but adds "if only," which turns the statement into a wish. That shift suggests the first line wasn't quite true in the way it seemed.
The title, "Sightseeing," points to looking at things from the outside, the way a tourist glances at a landmark. Read that way, "through these bodies" can mean we see the world only by way of our bodies, using them like windows or lenses. But the second line longs to see through them in a different sense: past them, to something beneath or beyond. The speaker seems frustrated by that limit.
The mood is quiet, wistful, and a little uneasy. With so few words, the poem leaves a lot of empty space, and that gap feels like the longing itself. It's also open to more than one reading, which is part of its pull.