It functions like visual art, but sticks in the head like poetry. The words we can extract from the poem are "loneliness", and "a leaf falls." Interestingly, "a leaf falls" is embedded within "loneliness." This is a meaning that can only exist in a visual mode that relies on visual arrangement of words. A short film of a leaf falling may suggest loneliness, but it can't carry the same impact as this poem, which literally embeds a leaf falling into the image of loneliness.