What is the theme of "The Lamentation of Old Pensioner"?

The theme of the poem is a common one in Yeats's late work: facing up to the harsh realities of growing old. The old man of the poem looks back wistfully to his younger days, when he was loved by many beautiful women. Yet now, as he seeks refuge from the rain under a broken tree, he considers that no woman would ever so much as think of looking at him.
The old man also reflects upon the fact that young men are once more "making pikes again / for some conspiracy." In other words, they're getting ready for a new uprising, which in the context of Irish politics at the time would've meant some kind of rebellion against British imperial rule.
Once upon a time, the old man might've joined them, but not now. All he can think about is time and how completely it has changed him. Some people accept the aging process gracefully but not this old pensioner. He positively hates being old; it makes him angry and resentful, so much so that he spits into the face of time that has transfigured him: in other words, made him old.
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