"Leda and the Swan" is essentially a depiction of a violent sexual encounter between a woman and a bird. If you find yourself sympathetic to the Ancient Greek perspective, you might think that the encounter is a divine and mystical experience. If you find yourself approaching the poem from a more modern perspective, you might be horrified. The poem caters to both viewpoints. Yeats's language seems to imply that the swan is violent and uncaring but also mysterious and seductive.