Poetry can be easy. We swim in a stew of ready-made metaphors; the would-be poet need only skim the surface, rearrange a few bits, and the superficial reader will nod approvingly. After all, poetry put together out of familiar flotsam doesn’t demand our attention, and paying attention is a lot of work.

Still, it is in our moments of paying attention that we are most alive. When poetry works, it is because we work with it to see the familiar made new or the new made familiar. Colleen J. McElroy, professor emeritus at the University of Washington and recipient of honors and awards too numerous to list, doesn’t bathe us in the broth of popular culture. This poetry works.

In her new collection, “Here I Throw Down My Heart” (University of Pittsburgh Press, 112 pp., $15.95), she writes on subjects that could easily devolve into cliché by a lesser poet — homelessness, our continuing wars, race, the degradation of our planet. In a poem titled “Diseases of the Earth,” she asks, “What will become of us / if our eyes are not opened?” Throughout this marvelous new book she makes it her job to open our eyes.

What makes these poems challenging is not some gratuitous surface difficulty — convoluted syntax, obscure diction, tenuous allusions that create amusing verbal puzzles, but that lead us farther from rather than nearer to the physical world. No, the challenge in “Here I Throw Down My Heart” is to the ways we have been conditioned to see (and thus not see).

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In “What Stays Here,” a woman soldier tells about the many wars she fights. Writing home, “I don’t tell / them nothing is what I expected it to be / and it’s what I don’t say that counts,” such as threats from her C.O., or sexual assault, or “the morning / when flares crisscross an oil-soaked sky / and the smell of sex and death fills the air.” She is at war with her own expectations, with a hierarchy that resents her very presence, with other soldiers who try to force her to fit their fantasies — and with a world gone so wrong that her own wrongs barely register: “I’d scream bloody murder but nobody comes running / when you scream bloody murder and there’s murder / all around.” “Bloody murder” is the hackneyed phrase that this woman happens to have picked from our store of prefabricated expressions, but the repetition strips it of its familiarity, just as for this woman “murder” has become more than a cliché, more than hyperbole.

In “Recruited” we hear how an African-American woman ended up in the army: “After high school / it was this or some dead-end job / so what choice did I have …” What a world, in which a young woman finds her only alternative to a “dead-end job” in a place where “black or white one body’s good / as another on the front line.” That “dead end” is dead language brought back to life by experience.