In the poem 'The Brook' the poet Lord Tennyson, describes the journey of the brook and brings out certain universal truths which form the central idea of the poem i.e. human life is temporary but nature is eternal.

The journey of the brook begins in the highest hill ranges, the dwelling places of aquatic birds like coots and herons. It makes a sudden movement and flows sparkling out among the ferns, bickering down a valley. The brook hurries down many hills, slips between the ridges and passes through many small villages, bridges, and a little town. Its chatter on its stony path babbles with gurgling laughter like a child as it flows into eddying bays. It flows by the farms of a man called Philip, fields in the brimming sunlight in a curving movement before it joins into an overflowing river. As the brook continues its excited and happy journey amid the flora and fauna of the countryside, it carries the flower and foamy flake along and happily offers refuge to fishes like trout and grayling. 

In the course of the journey, the brook meets various obstacles like stone, pebbles, and 'golden gravel'. Further, it steals quietly on grasslands, slides by the hazels moves aside the forget-me-nots, slips, glooms, glances, and murmurs under the night sky to finally join the brimming river.

This journey of the brook is a representation of nature as everlasting whereas human life is short-lived and transitory. This idea is clearly exhibited in the refrain of the poem -

 "For men may come and men may go,

 But I go on forever".