How does Cummings use metaphor in the poem, I Carry Your Heart With Me?

The speaker sets many of the poem’s metaphors in nature. Their love is at the “moon” (8) and the “sun” (9). It goes from the ground to the sky, traveling through “a tree called life” (12), through “the root and the bud” (11) to “the sky” (12) and even “the stars” (14). By associating their love with the natural world, the speaker suggests that it is something organic, something which makes sense in accordance with the laws of the universe.