Death

There aren't any overt references to death in the poem, but the speaker imagines humanity's alienation from nature as a kind of death. In addition, nature has become so alien to mankind that it is virtually unrecognizable as nature, as something that is moving. It is figuratively dead, in the same way that people are emotionally dead.

• Line 2: The poet claims people are killing their "powers" (probably something like our ability to feel), because they're so obsessed with "getting and spending."
• Line 4: The act of giving away our hearts is a metaphor for our alienation from nature. "Sordid boon" is a paradox because a boon is a reward or gift, which we usually think of as good, but the poet calls it "sordid," which is bad.
• Lines 9-10: Paganism is a thing of the past, which is why it is a "creed outworn." It's used up, out of style, dead, kind of like those jeans you wore in third grade.