Heralding the Classical Age
The titular swan is the mythological god of gods, Zeus and Leda is the mother-to-be of Helen of Troy. The Trojan—fought on the account of Helen—is to be viewed within Yeats’ somewhat cosmological view of civilization as occurring in cycles. The ultimate consequence of the vicious and violent rape by Zeus of the women who will give birth to the great beauty at the center of the Trojan War will be—ironically for Zeus—the end of the first two-thousand year cycle as it heralds the commencement of the Classical Age which would hold for two millennia until a different sort of rape—that of Mary by the God of Abraham and the conception of the Christ child insider her womb—would initiate the next cycle.
Godly Power and Human Agency
The final two lines of the poem suggest that perhaps some of the godly wisdom and power of Zeus worked its way into the genetic bloodstream of the mortal woman during the rape. The final line also hints that god Greek became indifferent to human life when those lies no longer intrigued them enough for interaction. The distance is thus made manifest between divinity and humanity while the longstanding acceptance of division creating a twain which shall not be crossed except in unusual and specific circumstances no longer applies. The infusion of some divinity within the strain of humanity looks forward past the Classical Age to the communion of god and man through the ritual of the Eucharist.
Irish Politics
As first conceived, “Lead and the Swan” was to be more forthrightly political, but in the working out of the verse, the potent obviously made the decision to move away from the literal almost entirely and situate meaning within figurative language. Yeats was a devoutly committed to the Free State movement in its dealing with an oppressive British government, but was equally committed to bringing independence about through legal and political systems rather than violence. The violent rape by an oppressive Zeus over a helpless mortal speaks for itself when understood in these thematic terms, but the poet was so rigid in his application of symbolic meaning and the necessity to come equipped with prior knowledge of mythological and historical associations allusions that it can be very easy to completely miss how this political theme can be applied.
