With regards to your question of how The Brook appears to be a symbol of life, there are many factors constituting its similarity.
To be clear, this answer refers to the Poem 'The Brook' by Alfred Lord Tennyson.
This can be read here:
The ways in which this Poem mirrors life are as followed:
- The brook emerges from the mountains in a way that mirrors birth, since it is very noisy, volatile and energetic. It is adamant on starting its life and accomplishing its life goal of joining the river, as man is born with the same energy and desire to succeed.
- In the early stages of the brooks journey, it encounters many obstacles such as stones and pebbles - synonymous to the journey of man, whom is met with similar such struggles. In its youth, it is very active and bold and takes such opposition in its stride, as does man, who is able to conquer via his youth and energy.
- The brook also takes with it many things, such as gravel, fish and silt. This can be compared to man bringing things and people with him in his journey, such as friends and emotions, which help or hinder his journey by some means.
- When the brook eventually begins to approach the river, its movement is delayed and becomes slower, which is a direct parallel to man, who's movements are mirrored by the brook towards the end of his life, growing soft, calm and gentle.
- The difference between the brook and the man is that the brook flows on eternally whilst man's life is terminated at his death.