What should I focus on when analysing the use of symbolism and imagery in W.B Yeats's 'Wild Swans at Coole'?

When analysing the use of symbolism in a poem, you should search for a central motif, the meaning of which seems to bear more weight that what may be literally construed upon first reading. In the case of 'Wild Swans at Coole', swans are the central metaphor, representing Yeats's love and longing for his muse, Maud Gonne. The inverted syntax in 'nine-and fifty swans' highlights the missing swan, underlining the painful incompleteness of Yeats's life. It is also important to note the ways in which symbols can change throughout a text. In this case, the swans evolve from something tangible and physical to something more mystical and ethereal. This symbolises Yeats's changing perception of muse; she transforms into an unobtainable, nearly other-worldly entity, which is captured in his description of the swans as 'brilliant creatures'. The more obsessed he gets, the less accessible Gonne seems. Birds are a fitting metaphor, since they, like the muse in the poet's eyes, inhabit a liminal space between earth and heaven. With imagery, it is crucial to remember that the term includes all the senses, not just the visual, which may be the most obvious approach. In 'Wild Swans at Coole' for example, the 'clamorous wings' of the birds creates a sense of disquiet which contrasts with the stillness of the setting. 'The bell-beat of their wings above my head' uses alliteration and onomatopoeia, possibly drawing on these literary techniques to create the ominous sound of funeral bells. This ties into the idea of the poet ageing and running out of time, foreshadowing the winter (symbol of death and barrenness) which will inevitably follow the scenes of 'autumn beauty' he describes.