Man, Shade, or Image (Symbol)
The ambiguously categorized mummy-like creature, who the speaker characterizes as "Shade more than man, more image than a shade," is a symbol of the passage between death and life. In this poem, the world of the living is framed as everyday and mundane, while the world of the dead is mysterious and spiritual. The being that can move between these two worlds, and induce others to do the same, holds an immense amount of power. This creature has just such an ability, and it introduces to readers the notion of movement between life and death. The fact that it is mummified makes it an especially suitable symbol of this passage between death and life, since mummies are dead bodies transformed by living beings—and indeed, since mummies are created to aid a body's transition to the spiritual realm.
Bird (Symbol)
The "Miracle, bird or golden handiwork" that so impresses the speaker is a symbol of the link between art and nature. In this way it is parallel to the previous symbol of the Image/Shade/Man, because, in Yeats's framework, the body, the physical, and nature are aspects of a single broad sphere—one that is opposed to the other sphere of spirituality, art, and the underworld. The speaker struggles to determine whether the bird is in fact a bird, brought about by natural processes, or whether it is instead a piece of "handiwork," an artistic rendering of a natural object. Moreover, like the mummified being in the previous stanza, this object gains power and beauty from its ambiguous, uncategorizable state. The speaker concludes that it is "more miracle" than anything else, made impressive and interesting precisely because it is ambivalent, at once a work of art and an animal.