Speaker
For much of the poem, we see the speaker as a child. He seems curious, perceptive, and adventurous. He also may be a bit rebellious or rash: the opening lines of the poem imply that he disobeys adults in order to explore the world, perhaps even putting himself in danger. Though he is single-mindedly focused on wells, that focus is multifaceted, encompassing a huge range of interests: plants and animals, the mechanics of physical space, sound and sight, and indeed himself—he likes viewing his own reflection. In other words, wells are a tool through which he can explore the world, and he is eager to do so.
In the closing lines of the poem, the speaker's vantage point is revealed, and we see that he is an adult. He now seems more withdrawn and cautious, no longer passionately exploring wells so as not to seem childish or narcissistic. However, he now appears to be a poet, and he uses the tools of poetry to understand himself and the world around him just as he once used wells to do so.
