RELATIVITY
This is whatever can be measured between us.
For instance, two birds share one sign, tail feathers
touching, heads back in song, a heart of gray sky framed
between them. But look again, for each line clocks
a difference. One breaks off, another begins. Attention flows
to the details. Then it’s back toward this upward glance
into some larger change of one bird now missing;
the gray heart gone; the sky cold, clear, and alone there.
Prometheus Unbound 