The poem is a tiny scene with a sharp turn in the middle. On Christmas day, the world outside looks white, and the speaker calls it "white with angels of ice." The image could mean frost patterns, ice-covered branches, or snow glinting in the light. Either way, it borrows the language of the holiday and gives it to the weather. The title, "Heard on high," echoes the carol phrase about angels, so the cold morning gets a faintly sacred glow.
Then the second stanza pulls the focus inward. The speaker thinks of "last night's book" and feels how far away it is from "our public joy." The word "public" matters here. Christmas is shared and loud, while reading is quiet and solitary. The speaker seems a little caught between the two, perhaps still living in the private world of the book while the day demands cheer.
The mood is hushed and reflective, with a touch of wistful distance beneath the festive surface.