In terms of the themes of Auden's poem, I don't think you can go ver far without discussing the horrific nature of war. Auden is fairly masterful in how he transforms the Classical depiction of war into a Modernist context, one that reveals a darker side than what the Classical purists might suggest. The idea of Thetis, mother of Achilles, approaching Hephaestus for a shield to take to battle traditionally indicates the images of glory, austerity, and an almost singular embrace of the war fighting culture. Yet, as the lame blacksmith god forges away, both we and Thetis are horrified by the images he presents of desolation, death, vengeance, and emptiness that war represents. This becomes one of the major themes of the poem in that there is an emptiness to war, one that does not breed solidarity and forge a sense of communal identity. Rather, it creates bitterness in the survivors and the dead are the only constant force. The boy throwing a stone at a bird is the only remnant of this social order, one in which children become the bearers of the violence brought on by adults. The images that are present on the shield help to represent this, enhancing the thematic implications of the poem. The poem's revelation that Thetis only grasps becomes the lasting image of the poem in that Achilles will die in the Trojan War. This becomes the final truth and the main theme of the poem in that war is not something that brings out the best in human beings, but rather its worst. Those who glorify the war fighting culture are ones who bring this out, individuals who praise the Classical notion of war. Auden repudiates this with the themes that come out of his poem.