Our speaker is invisible. We know he is wise, because he apparently knows what depends upon a red wheelbarrow, while we are stumped. We know he is an appreciator of life, and, in particular, of the small things in life. For some reason, our speaker reminds us of someone who has lived a long and full life. There's something about the way in which our speaker reflects so fully and simply on an object as ordinary as a wheelbarrow that makes us think he has learned a thing or two about life. He seems to be a wise, somewhat lonely, lover of life.