Dickinson structures the entire poem as an experiment in three stages, each marked by precise time stamps. At 3:30, a single bird propounds—a term from logic and law meaning to offer a proposition for examination. The bird doesn't just sing; she advances a cautious hypothesis, testing whether dawn will answer.
By 4:30, the experiment succeeds. Subjugated is a conquest word—the test has been dominated, proven. What was tentative becomes principle, a scientific law. Dickinson uses silver for both its sonic quality (the bell-like clarity of birdsong) and its suggestion of something refined, proven, valuable. The singular melody has supplanted all alternatives, the way a successful theory replaces competing explanations.
The final stanza completes the abstraction. By 7:30, neither element (raw material) nor implement (tool/method) remains visible. The bird has dissolved into pure presence—not a physical thing but a proven fact. Circumference is Dickinson's term for the boundary between what we can know and what we can't, appearing in dozens of her poems. The bird hasn't simply flown away; she's crossed from the material world into the realm of established truth, leaving only the space she occupied.