This is a less obvious and central theme, but we think it pops up in really interesting ways. "The Day is Done" has quite a bit to say about how literature comes down to us from the past. In a sense, this is about literary tradition, but not in the sense of a pile of musty old books that you have to read. That's exactly what the speaker is <em>not</em> after here. What he thinks is really great is the way that real, raw emotions can be stored in a poem, and can come back to life when it's read aloud. Sound a little wacky? Maybe so, but that's the kind of poetry magic we love around here.
The speaker in "The Day is Done" is trying to forget the past, to push away his memories and the traditions of poetry. In doing that, he is trying to focus his readers entirely on the present moment.
Although memories of work and suffering are clearly painful to the speaker, he heals himself with another kind of memory: the beautiful music that is stored in poetry.