Musée des Beaux Arts (title)
This isn't exactly a quote. But it's the title that sets the stage for a poem that might otherwise pass for a meditation on anything but art. Which is why it has to emphasize that the poem's occasioned by a visit to a museum. Of fine art.
The Old Masters; (2)
Although we might not know it the first time we read it, the Old Masters referred to here are the great painters whose paintings grace the museum we talked about above. We know, we know – it's not a huge and deliberate reference. It's just a backdrop – a prompting for the thoughts that emerge when you see an awesome piece of art. Hey, you catch more flies with honey, right?
In Breughel's Icarus, for instance: (13)
The reference to Brueghel here does two things: it grounds the poem in a concrete example (yay!), and it transfers our attention from a group of people to a single painting. Remember what life was like before the internet? (OK, we're just teasing. We don't, either.) But Auden's first readers might not have been able to see Breughel's painting right away…they just had to take his description on its own terms.