Brenda Hillman's poem "Air for Mercury" was published in her 2001 collection Cascadia, which most critics acknowledge is Hillman's most ambitious work, if not her most accessible work. The volume was inspired by Hillman's love for her adopted state of California. Cascadia refers to the prehistoric landmass that predates California and America's West Coast—a landmass that was submerged under the ocean more than 100 million years ago. In Cascadia, Hillman uses this ancient geological occurrence as a springboard to map the various geological and cultural characteristics of modern-day California. But, as Hillman herself notes in an online interview with Poets & Writers magazine, "The main geography of the book is the idea of mind-as-earth." The book, then, becomes an exploration of the shifting tectonic plates of the human mind, what she refers to as "the ceaseless slow and potentially violent nature of change . . . the upheaval of ideas or feelings." This abstract notion permeates the book and is present in "Air for Mercury," which some students may find confusing at first. In the poem, Hillman seems to incorporate several different image systems and concepts in one shifting mass that defies cohesiveness. But by viewing the poem in terms of the human "change" that Hillman notes, the poem begins to make sense, and its dominant themes, the loss of religious faith and comprehension as modern society moves toward secularization, begin to shine through. A copy of the poem can be found in Cascadia, published by Wesleyan University Press in 2001.