(5) Tree Line
To make this poem easy, you only need to know two key things: 1) William Butler Yeats was a super-amazing poet; and 2), there's a long tradition of writing poems (called elegies) about famous dead people. Combine those two little facts and suddenly this poem isn't so bad. It's an elegy written to commemorate the death of William Butler Yeats. See? That wasn't so hard.