As the brook flows along, it carries with it a flower blossom, a trout, and a "grayling," which, like a trout, is a freshwater fish. Less literally, it carries, as it is pushed along by the breezes, waves and foam, as well as the sunbeams that "dance" against its shallow parts.
In celebrating the brook, Tennyson shows its interconnectedness with the life along its banks. Land life and water life mingle together, the forget-me-nots along the shore "moved" by the brook's lively motion.
Tennyson also personifies the brook, which tells its story as if has the awareness, senses, and insight of a human being. It is cheerful, merry, and ever-observant of the nature all around it, such as the grass, the willow weeds, lawns, and, at night, the moon and stars. It understands itself to be the backdrop to these elements of nature, all of them working together to create beauty.
The brook also displays a human understanding of its timeless or eternal quality. It contrasts itself to human life, which comes and goes, saying that it, the brook, goes on forever. From the point of view of the brook, humankind is simply one of a myriad of elements that make up a complex natural world.