How does Kent Haruf use imagery in Plainsong?

In the opening pages of the novel, the author gives a definition: "Plainsong—the unisonous vocal music used in the Christian church from the earliest times; any simple unadorned melody or air." The latter part of the definition is applicable to the language and meaning of this novel. Plainsong is not a religious novel in any way. It is never mentioned. It is, however, full of unadorned yet beautiful, even poetic, language. These poetically visual passages are often found in the parts of the novel that describe the regional setting, whether it is a windmill on a secluded ranch or a seldom-used railway depot.