The speaker watches a young woman crying and gently steps back, treating her grief as something holy. He does not try to comfort her or stop her tears; instead he says that if he carried the fears she feels, he too would weep without wanting relief. Her sorrow is open and natural, while his own is hidden and wordless.
His pain only takes shape when he turns it into “measured rhyme”—poetry. The final image is quiet and musical: at the time when the blackbird’s song softens, his heart begins to sing through verse. So the poem contrasts two kinds of sadness—one expressed openly, one held inside and transformed into art. The mood is tender, hushed, and a little mournful, like someone speaking softly at the edge of another person’s grief.