That is no country for old men (1)
Yup. It sucks to be old in the country where our speaker is from. The emphatic tone of this first line frames the entire poem as a search for everything that the old country isn’t.
An aged man is but a paltry thing, A tattered coat upon a stick, (9-10)
Although the first stanza of "Sailing to Byzantium" emphasizes the natural world, the start of the second stanza seems to be strangely unnatural. Age strips the very flesh from people’s bones, leaving nothing but the clothes they once wore.
Consume my heart away; sick with desire And fastened to a dying animal It knows not what it is; (21-23)
Yeats seems to be distinguishing the heart of the speaker from the mere animal nature of the speaker’s body. Stuck in a body, the heart can’t achieve its true potential – as art.