The speaker watches someone they love, or admire deeply, gathering goldenrod in a field. The scene returns at the end, now brighter: sunlight seems to slip out of the person's hair, their feet are sunk in wet grass, and their arms are full of flowers. In between, the poem drifts into stranger territory. The beloved breathes "like a scientist," smells like discarded second-hand books, and is imagined as a gift to experimenters and to men who fight, cry, or wait.
The speaker's feelings seem a mix of devotion and restlessness. The repeated "I cannot" lines suggest someone unable to settle, pulled between the cold, enclosed "laboratory" and the sun outside. Judging by the imagery, the poem sets precise, clinical language against open fields and warmth.
The mood is quiet, tender and slightly uneasy. Repetition makes the watching feel like a memory the speaker keeps replaying, and the final single line leaves the image glowing and still.