I need it to really sink in that between the dog and the very young human, both of them are experiencing a kind of joy and delight they literally did not know was even possible before this.

That baby is very young and the dog has no instincts about the springy rubbery environments its ancestors didn’t encounter because they don’t exist. How rare is it, how splendid, to watch two souls on this Earth, so different and yet so alike in their joint delight over a source of joy that they’ve never experienced before