The poem traces a child's sense of the world and what happens when that vision fades. At first, the child’s faith is entire and untroubled — as whole as his principle, as wide as sunrise on new eyes. He laughs at scruples and trusts everything but Paradise, which alone seems unreal. He feels his domain so vast that Caesar seems a baseless emperor — ruler of nothing yet commanding all. It’s a state of joyful, unbruised confidence.
Then the growing happens, “bye and bye.” The child learns that his pretty estimates of prickly things were mistaken. The skill he gains is a sorrowful certainty: instead of kings, he learns to anticipate men — flawed, ordinary, real. The mood shifts from sunlit expansion to a quiet, knowing ache. The speaker doesn’t condemn this; she simply names it, making the loss feel both inevitable and quietly tender.