In just four lines, Teasdale describes the moment when day gives way to night. The speaker watches the sky and sees it as a small drama: dusk is "stately" and "tragic," a grand scene that reaches its "perfect close." Then two heavenly bodies trade places. The pale evening star sinks, and a red moon climbs up in its place.
The speaker never says "I feel," but the feelings come through in the word choices. Calling dusk a tragedy suggests something beautiful is being lost, yet "perfect" tells us the speaker admires how neatly it ends. The star is "virginal" and white, which makes it seem pure and delicate. The red moon that follows is warmer and bolder, so the poem moves from cool stillness to a richer color. The mood is hushed, formal and a little wistful. It feels like watching a curtain fall and rise again, with the speaker as a calm, appreciative audience.