Why does yeats say terrible beauty is born?

Yeats uses the phrase "terrible beauty" to capture the paradoxical nature of artistic and political struggle, particularly in the context of the Irish nationalist movement. This beauty emerges from chaos, violence, and sacrifice, suggesting that profound art and meaning can arise from turmoil and suffering. The term reflects the complexity of human experience, where beauty can coexist with pain and tragedy, highlighting the transformative power of such experiences. Ultimately, Yeats suggests that this "terrible beauty" is a product of both the deep emotional and physical struggles inherent in the pursuit of identity and freedom.