Yeats contests the cliché that beauty "passes like a dream,' noting that beauty has been responsible for major tragedies of human violence, including the sack of Troy and the death of Usna's children. He insinuates that Maud Gonne's beauty is capable of inspiring such destruction as well.
Yeats then suggests that while most human life passes by like a dream, Maud Gonne's "lonely face" lives on. He even insists that immortal beings - archangels - bow down before Gonne's unchanging beauty, suggesting that her being existed alongside God before the world began. The world, indeed, is a mere grassy path created for her to tread.
Yeats wrote this poem to Maud Gonne, with whom he was deeply in love. He often compares her to Helen of Troy, arguing that her beauty, like Helen's, is capable of wrecking turmoil between nations. Indeed, as Gonne is a representative of Ireland, this comparison suggests that her beauty embodies the strife between Ireland and England, which is especially fitting given that Gonne was a fierce Irish nationalist. The reference to Usna's children in the same stanza likens her to Deirdre, an Irish heroine who was destined to bring suffering on the area of Ulster, because too many men fell in love with her.
Before its publication, George Russell objected to the final stanza of the poem (the poem had originally only had two stanzas). He thought that it lowered the quality of the poem because it added a sentimental note. This last stanza is closely tied to the circumstances under which the poem was written - after Yeats and Gonne had gone hiking together. The final lines - "He made the world to be a grassy road / Before her wandering feet" - seem to allude to this hike. Moreover, the concept of "wandering" possibly captures Yeats's perennial frustration that Gonne would not take him as a lover or a husband.