birds darting in low shrubs. (15)
In some traditions, birds are a symbol of the human soul. Thank goodness for symbols. We take this line as the most promising sign yet that the human spirit may survive death. Unless, of course, the birds are just birds, and the speaker is just describing the cyclical experience of perennial plants.
returns from oblivion returns
to find a voice: (18-20)
The opposite of nothing is something, right? So someone who returns from oblivion (the nothingness of death) has to exist in some form. Unlike the wild iris, humans are not reborn each spring. But if the poem is a spiritual allegory, it would seem to suggest that our spirits live on after death. Shmoop is delighted to hear that this new life includes a new voice: we'll need it to shout "Hallelujah!"