The gyre, a circular or conical shape, appears frequently in Yeats’s poems and was developed as part of the philosophical system outlined in his book A Vision. At first, Yeats used the phases of the moon to articulate his belief that history was structured in terms of ages, but he later settled upon the gyre as a more useful model. He chose the image of interlocking gyres—visually represented as two intersecting conical spirals—to symbolize his philosophical belief that all things could be described in terms of cycles and patterns. The soul (or the civilization, the age, and so on) would move from the smallest point of the spiral to the largest before moving along to the other gyre. Although this is a difficult concept to grasp abstractly, the image makes sense when applied to the waxing and waning of a particular historical age or the evolution of a human life from youth to adulthood to old age. The symbol of the interlocking gyres reveals Yeats’s belief in fate and historical determinism as well as his spiritual attitudes toward the development of the soul, since creatures and events must evolve according to the conical shape. With the image of the gyre, Yeats created a shorthand reference in his poetry that stood for his entire philosophy of history and spirituality.
Swans are a common symbol in poetry, often used to depict idealized nature. Yeats employs this convention in “The Wild Swans at Coole” (1919), in which the regal birds represent an unchanging, flawless ideal. In “Leda and the Swan,” Yeats rewrites the Greek myth of Zeus and Leda to comment on fate and historical inevitability: Zeus disguises himself as a swan to rape the unsuspecting Leda. In this poem, the bird is fearsome and destructive, and it possesses a divine power that violates Leda and initiates the dire consequences of war and devastation depicted in the final lines. Even though Yeats clearly states that the swan is the god Zeus, he also emphasizes the physicality of the swan: the beating wings, the dark webbed feet, the long neck and beak. Through this description of its physical characteristics, the swan becomes a violent divine force. By rendering a well-known poetic symbol as violent and terrifying rather than idealized and beautiful, Yeats manipulates poetic conventions, an act of literary modernism, and adds to the power of the poem.
Yeats employs the figure of a great beast—a horrific, violent animal—to embody difficult abstract concepts. The great beast as a symbol comes from Christian iconography, in which it represents evil and darkness. In “The Second Coming,” the great beast emerges from the Spiritus Mundi, or soul of the universe, to function as the primary image of destruction in the poem. Yeats describes the onset of apocalyptic events in which the “blood-dimmed tide is loosed” and the “ceremony of innocence is drowned” as the world enters a new age and falls apart as a result of the widening of the historical gyres. The speaker predicts the arrival of the Second Coming, and this prediction summons a “vast image” of a frightening monster pulled from the collective consciousness of the world. Yeats modifies the well-known image of the sphinx to embody the poem’s vision of the climactic coming. By rendering the terrifying prospect of disruption and change into an easily imagined horrifying monster, Yeats makes an abstract fear become tangible and real. The great beast slouches toward Bethlehem to be born, where it will evolve into a second Christ (or anti-Christ) figure for the dark new age. In this way, Yeats uses distinct, concrete imagery to symbolize complex ideas about the state of the modern world.