The poem begins with a beautiful scene: a winter morning "as fine as jade," clear, cool, and almost precious. But the mood turns quickly. In the second stanza, an "old sorrow" gains "new ice," as if the cold outside is seeping into something the speaker has carried for a long time. The grief isn't new, but the season hardens it and makes it heavier.
The last stanza is the strangest and most revealing. The speaker asks who will trade "a wren for a canary." A canary is a bright, showy songbird, often kept in a cage, while a wren is small, plain, and brown. It's hard to be sure what the speaker means, but the question sounds like a wish for something humbler and more honest than a pretty, borrowed cheerfulness. Perhaps it's a plea for a small, real song in a hard season. The mood is quiet, wistful, and a little lonely, with beauty and sadness sitting side by side.