Yeats’s poem is built around the theme that singular acts of violence can lead to violence on a much wider and larger scale, creating cycles of violence and trauma. While other poets and artists over the centuries have sometimes depicted the encounter between Leda and Zeus as a consensual act of seduction (See: Literary Context), Yeats’s speaker is explicit in describing rape. The poem’s first words are “A sudden blow” (Line 1), stressing both the unexpectedness of the encounter (since it is “sudden”) and the immediate violence in Zeus’s approach—it is a forceful “blow” that leaves her “staggering” (Line 2), not the welcome overtures of a lover. This explicit violence pervades the encounter, with Leda “helpless” (Line 4) beneath the swan’s powerful advances, “terrified” (Line 5) in her futile resistance, and “caught up” (Line 12) and “mastered” (Line 13) by the swan against her will. The encounter is therefore an unambiguous violence.

In the final stanza, the speaker alludes to what will happen due to this rape, drawing a clear causality from Leda’s conception of Helen to the devastation of the Trojan War:

A shudder in the loins engenders there

The broken wall, the burning roof and tower

And Agamemnon dead” (Lines 9-11).

Just as Leda has been overpowered and violated by Zeus, so too will the city of Troy be overpowered and violated by the Greek army led by Helen’s spurned husband, Menelaus, and his brother Agamemnon.