The speaker looks at a portrait of a Florentine lady and tries to name what shaped her expression: fine objects, private dreams, spring dusks, a sigh in a hidden lane. These are not ordinary biography; they suggest someone dreamlike and removed, beautiful but touched by solitude.
That feeling grows stronger in the second stanza. God made her, the speaker says, out of lonely things—and to bring her into the world, he had to topple a hundred towns into darkness. It is an unsettling image: her beauty seems to cost something, as if it comes from loss and ruin. The mood is reverent and melancholy at once. The speaker feels awe before the face in the portrait, but also a quiet sadness, as though looking at something lovely that could never quite belong to ordinary life. That blend of wonder and sorrow is what lingers.