The poem catches a small, odd moment: the moon still hanging in the sky after daylight has arrived. The speaker suggests that a moon nobody pays attention to would simply vanish into the brightness of noon, swallowed by the ordinary day. The phrase "any enemy of change" is a little puzzling, but it seems to link that fading to everything that keeps things the same and unnoticed.
Then the focus drops to a wren, which goes about its business in a "matter-of-fact" way. Next to its easy liveliness, the speaker feels stuck: "still and cold / as a dead clown." That image is strange and a bit unsettling, mixing something once playful with lifelessness.
The mood is quiet, wry, and slightly bleak. The speaker seems to see himself in the faint moon, present but barely noticed, while the bird simply gets on with living.