This line sums up the speaker’s relationship to his father. The speaker didn’t thank him, or even realize all that he’d done for his family. Nice work, kiddo.
I’d wake and hear the cold splintering, breaking.
When the rooms were warm, he’d call,
and slowly I would rise and dress, (6-8)
Here, we see the speaker enjoying a nice warm Sunday morning in bed, while we know that his father was up in the cold winter a.m. There’s such a distinction between the speaker’s experience and his father’s.
fearing the chronic angers of that house,
Speaking indifferently to him,
who had driven out the cold
and polished my good shoes as well. (9-12)
Now we find out that the speaker, in his youth, feared his father, and thus was cold to him (emotionally). Maybe his father wasn’t the snuggliest dad around, but he sure knew how to provide for his family. The speaker starts to acknowledge his father here, and draws a contrast between how he related to him (indifferently) and all that his father had done (warmed up the house, polished his shoes), which shows just how not indifferent the old man was. We’re starting to get a sense that the speaker, as an adult, recognizes the misbegotten feelings of his youth.
What did I know, what did I know
of love’s austere and lonely offices? (13-14)
Everything becomes clear in these final lines. By asking this question, the speaker acknowledges that he knew nothing of love in his youth. The implication is that the speaker now understands his father’s love for and dedication to his family. Take that, youth! In this poem, wisdom (especially the emotional kind) comes with age.