Unexplained symbols! The weirder the better. Falcon, sphinx, "rough beast," and Bethlehem: what’s the connection? You figure it out! Yeats isn’t giving any help. This is a trait that many of Yeats’s most famous works have in common. He likes to take symbols from a variety of sources – the Bible, history, folklore, and his own plays; put them in the blender; and Presto! A Yeats poem.