(Please refer to the previous post to read the poem.)
"Wherever I am / I am what is missing."
The speaker feels able to "complete" any environment. This signals power; nothing is finished without him/her. "In a field / I am the absence of field." The speaker "always" provides the definitive other by which the environment can be identified. How can we know what a field is if we don't know what a field is not?
However, this idea also suggests that the speaker is forcibly fluid in his or her own identity. What can the speaker be other than "not" what is in the environment? The speaker can only be defined in a negative term: not a field, not the air. The speaker's own identity is fluid and transient, while the surroundings use the speaker to form their identities. Add to this the responsibility--even obligation--to be that which keeps things whole and defined. I sense anxiety and sadness in this poem, and a feeling of resignation.