The poem begins with a familiar childhood warning: never look straight at the Sun. The speaker says they obeyed at first, but not just because adults said so. They obeyed out of instinct, a kind of reverence for the warmth, as if the animal part of them knew to shield itself with its eyelids. The Sun becomes a symbol of something overwhelming and life-giving, and looking at it suggests growing up, or learning a truth that can't be unlearned.
Once the speakers are no longer young, they look, and "what we saw / changed us forever." The tone shifts from tender to uneasy. They feel small before a power they can't face, and their act of rebellion feels both thrilling and fatal. Now they sit with their eyes closed, dazed, waiting for the after-image to fade and afraid of what follows. The closing line returns to childhood, and it reads as longing. The mood is wistful, shaken, and quietly fearful, like someone mourning an innocence they chose to lose.