In "Sailing to Byzantium," W. B. Yeats presents the idea that the immortality of art and the essence of the soul rise above the fleeting nature of the physical world. In a well-structured essay, discuss how Yeats employs imagery, symbolism, and structure to highlight the contrast between the deteriorating natural world and the timeless realm of art and spirit. Your essay should clearly assert what Yeats ultimately conveys about the relationship between mortality, artistic creation, and the human yearning for permanence.

In "Sailing to Byzantium," W. B. Yeats suggests that the immortality of art surpasses the fleeting nature of the physical body, placing the timeless realm of artistic and spiritual creation above the mortal, sensory experience of nature. In a well-organized essay, defend, challenge, or qualify Yeats's assertion that art and artistry provide a more significant form of existence than biological life. Utilize specific poetic devices — including imagery, symbolism, tone, and structure — to bolster your argument, and examine how the speaker's journey from Ireland to Byzantium serves as both a literal and metaphorical transformation.