You should describe what the poet writes about and how he uses language to convey his thoughts and feelings.
In W.B Yeats poem "When You Are Old," an anonymous narrator requests of a former lover to remember her youth and his love for her, the poem continues to tell the tale of this unrequited love the narrative persona feels. Unrequited love is the theme for this poem and is illustrated through a number of different techniques.
There are three stanzas in the poem, each consisting of four lines. All three stanzas correspond to the same rhyming pattern of a, b, b, a. The poem is written in the form of an ode, it is written in second person addressing a subject. The poem flows very softly which disguises some of the deeper, harsher meanings of the words.
The poet’s language changes as the poem progresses from stanza to stanza. In his opening, he instructs an "old and gray" woman "full of sleep" to "slowly read" a book of memories from her youth. As he moves to the second stanza, Yeats uses alliteration to remind his former lover of her "glad grace" that was loved by many. He reminds her of “how many loved” her looks and he, who loved her for her “pilgrim soul” and that he loved her even as she grew less beautiful and as she changed in time. The once warm and reminiscent old woman is reminded of an eerie and faded love that was never fully resolved, a faded love that may indicate a hidden feeling of remorse from the narrator, “But one man loved the pilgrim soul in you…the sorrows of your changing face”. The tone shifts with the language as Yeats describes the “sorrows”.
Yeats calls the old woman to "Murmur a little sadly" about those former days now that he is through with pacing “upon the mountains overhead" and has now hidden “his face amid a crowd of stars." These details provide a peek into the narrator's torn-apart heart as he evokes from her memories how patiently he waited for her as the sorrows of time wore away at her fragile beauty. His unconditional love for her was ignored and eventually forgotten as just another one of her "false" and "true" loves among the stars in the night sky. The narrator seems to be full of regret that she never took advantage of his love for her, and that he had to watch her age without his love from afar.
This sad and reminiscent poem is not meant to make an old woman regretful, but to keep a young woman from ignoring the narrator and making the wrong decision, a warning to her. The narrator is calling upon a woman in her youth to, once she is aged, remember the days he was in her life and very much in love with her. Obviously, he wants her to remember him for his unconditional love for her, and how she is choosing to ignore it in the present.
Yeats has succeeded in writing a poem full of pensive regret and memories evoking the sense of aging by using a wide vocabulary of profound words. He created clear images through his use of adjectives and metaphors.