Death and the passage of time
The speaker's gloomy mood in the poem stems from his realization that so much has changed since he began counting the swans at this lake nineteen years earlier. At its heart, the poem is a meditation on the fact that some things are oblivious to the changes wrought by time on human lives. So much has changed for the speaker since he first observed the swans; yet the swans and the woods are still the same—as beautiful as ever. This makes the speaker feel happy and sad at the same time, because although he is sad about all that has changed, he is also glad that the swans will continue to exist and could perhaps provide the same joy they gave to him to some other observer. The poem is both a meditation on aging and the passage of time, and a tribute to things that are immune to change.
Nature
"The Wild Swans at Coole" juxtaposes its speaker, who is aging and who has lost much of his former energy, with nature, which is eternally suspended in time, constantly dying and rebuilding itself again and again. Nature is one of the poem's central themes, representing both a reflection of the speaker's interior landscape and a divine force independent of human frailty.
Even though the speaker and the human world he knows have changed during the nineteen years since he started visiting the lake, he observes that the swans and the lake remained unchanged. The poem concludes with the idea that while human generations will die and new ones will be born, nature will remain the same, beautiful and eternal. It is in nature that man can find himself—fractured and changed though he may be—as part of a much larger, eternal whole.
Loss
The collection of poems for which this poem provided the title was dedicated to Lady Gregory’s son, Major William Robert Gregory, who died in World War I. It is possible that he is symbolized by the sixtieth swan, the one who disappeared, leaving the count of swans at fifty-nine; the sixtieth swan may also be Maud, or even the speaker's youthful self. The poem’s mournful mood makes it a meditation on the way that time changes humans, youth and beauty fade, and loved ones are lost.
Self-Discovery
Many of Yeats' poems, especially those in the collection The Wild Swans at Coole, invoke fantasies of self-discovery and the self-actualization that the speaker wishes to attain.
The poem begins with the speaker departing from society and walking into the woods to meditate on his life. He places himself in a quiet space where he can look back on himself without being distracted or influenced by anything. He detaches himself from the pollutions of the modern world, and thinks back on memories that belong only to him. Yeats did this in his real life, too, moving into a tower in County Galway, far from the business of Dublin so he could focus solely on his writing.
"The Wild Swans at Coole" does not directly mention the brutality of World War I or the violence in Ireland that tainted the time period in which it was written. Instead, it focuses on the speaker's own aging process, his own fractured relationships, and his own creative process. It thus creates space for Yeats to come to a sort of self-discovery that allows him to understand his relationships to higher, more eternal things like love and art, and it ultimately allows him to find peace with his own mortality.
Loneliness
This poem is mostly a tale of a solitary wanderer, caught up in his memories, and it trembles with loneliness at every turn. The speaker is lonely, even jealous of the swans, who are able to swim with their lovers, escaping the ravages of time and rejection (except for the missing sixtieth swan and its partner, who have somehow been separated).
The speaker is conscious of his own unimportance in the grand scheme of things. He talks about the swans jealously, like he is describing a youthful lover who he knows will move on after he is gone. (He may have been describing Maud Gonne, who did move on and married someone other than him).
Even the streams seem companionable, providing a watery embrace for the swans that they carry, but the speaker is unable to find any real comfort. Instead he is left only with his memories, and the words he has to write about them. His experience is a lonely one, and he knows he will disappear into nothingness one day.
Eternity
Despite the fact that the poem is primarily a melancholy piece, there are some silver linings. Not everything changes, Yeats seems to say. Some things last forever. In the poem, the things that intimate eternity are the swans, which he observes continuing to live and love as they always have, unaware of the passage of time. The swans' love for each other, and their passion and dreams, never die. (Now it seems like Yeats is projecting a bit of himself onto the swans). Even after the speaker leaves, he knows that the swans will continue to live their lives. This touches upon the poem’s central theme that some things in the world are able to transcend time, escaping the forces of change and remaining always the same.
Immortality through creativity
As much as this poem fixates on the speaker and his own perception of aging, it also focuses on immortality, which is expressed by the reverent descriptions of the swans that contrast with the more sorrowful imagery reflecting the speaker's mortality.
The swans are "unwearied still," Yeats writes, riffing on their ageless beauty. Like the swans, this poem itself has long outlived Yeats, retaining its beauty to this day. In his art, and in his reverent appreciation of the swans, Yeats was able to access a form of immortality that transcended his own mortal self and that lives on in each reader of this poem. In a way, words themselves are like swans, fluttering across the page and into the minds of thousands of readers across continents and time, bringing pangs into the heart of each reader no matter who they are. Some things are truly unchanging, Yeats seems to be saying, and creativity, accessed through memory and imagination, can be a pathway to this eternity.
