In the fourth stanza of his poem "A Prayer for my Daughter" Yeats refers to 'Helen' and 'that great Queen'. How do these mythological references...

In this poem, written to his infant daughter as a storm howls outside, Yeats fears for her in the new, post-World War I world, and hopes that can she can grow into a woman of beauty, good manners, kindness and independence who can marry into a stable and traditional home. In the third stanza, he muses on his wish that she be beautiful, but not so beautiful that it makes her vain or proud. Thoughts...

In this poem, written to his infant daughter as a storm howls outside, Yeats fears for her in the new, post-World War I world, and hopes that can she can grow into a woman of beauty, good manners, kindness and independence who can marry into a stable and traditional home. In the third stanza, he muses on his wish that she be beautiful, but not so beautiful that it makes her vain or proud. Thoughts of beauty no doubt recall to Yeats' mind Helen of Troy, who was considered the most beautiful woman in the ancient world. She is the "Helen" who opens the fourth stanza. Thinking of Helen's fate, married to the "fool" Paris, Yeats hopes his daughter will end up with a better choice of husbands. Paris married Helen because he was besotted with love for her beauty, but this choice--this "being chosen"--led to the disastrous Trojan war and Paris's death. 

Yeats then thinks of another figure who had a less-than-perfect marriage, "that great Queen, that rose out of the spray," Venus (known in Greek mythology as Aphrodite), the goddess of love who chose to marry Vulcan, the "bandy-legged smith." However, Aphrodite cheated on him (after all, she was the goddess of love) and the two could never have children. This is another fate Yeats would like his daughter to avoid, as he muses on the marriage pitfalls women can fall into. He notes at the end of the stanza that the "Horn of Plenty is undone" by the "crazy salad" of marriage problems.

This poem was written only a few months after Yeats' famous poem "The Second Coming," in which he fears that anarchy and chaos is coming into the world. Wishing his daughter to be safe from some of the problems faced by Helen and Aphrodite fits well with the theme of a poem that "prays" for a sane life and future for her. At the end of the poem, Yeats returns to the image of the "Horn of Plenty" that he mentions Helen and Aphrodite not having in stanza four, now calling it a "rich horn" and finding it in an orderly, ceremonial married life.