This is a beautiful poem about a beautiful painting. Browning writes the poem and first-person and refers to the painting of the Duchess with a lot of reverie. He appears in awe of the painting’s beauty. He describes the Duchess refers to the audience as strangers. Perhaps he’s trying to say that all people with the paintings are strangers. They come to the museum and they look at paintings in order to connect to some part of the past or to the person pictured in the painting. And though these people tend to leave museums feeling as if they’ve met someone, they haven’t really met anyone at all, just painting on the wall. And thus they remain strangers.