A sudden blow: the great wings beating still Above the staggering girl, her thighs caressed (lines 1-2)
Leda's helplessness in the poem is linked to the "blow" she receives at the start of the poem. The assault has a vertical direction: she is knocked off her balance as the bird descends from above. She clearly lacks the ability to prevent what follows.
her nape caught in his bill, (line 3)
The swan gains control over Leda by grabbing the back of her neck with his bill. He wraps his neck around Leda. Although this act is an expression of raw power, critics also view it as an image of graceful and mysterious splendor to the reader's mind. The poem contains a tension between beauty and violence.
How can those terrified vague fingers push The feathered glory from her loosening thighs? (lines 5-6)
The second stanza contains the justification for Leda's lack of free will. She is too frightened ("terrified") and confused to take any course of action to stop what's happening (her fingers are "vague" about how to resist). The speaker's use of a rhetorical question suggests that the encounter is fated.
And how can body, laid in that white rush, But feel the strange heart beating where it lies? (lines 7-8)
Leda never gains a clear view of the swan. She sees only a "white rush" of feathers. These lines may imply that Leda's resistance to the swan is weakening. She may now find him to be an object of fascination.
The broken wall, the burning roof and tower And Agamemnon dead. (lines 10-11)
Leda's pregnancy fits into a pattern for the fate of world history. Ironically, she never has less free will than in the question of whether to become an important figure in history.
Being so caught up, So mastered by the brute blood of the air, Did she put on his knowledge with his power Before the indifferent beak could let her drop? (lines 11-14)
The final lines of the poem crystallize Leda's situation: she is "mastered" by the fateful powers of the universe, but she has the opportunity to demonstrate her free will by acquiring knowledge of her role in history. The poem leaves open the question of whether she does.