Symbolism, Imagery, Allegory
The river is a central symbol in Siddhartha, representing unity and the eternity of all things in the universe. At times of great transition in his life, such as when he leaves the Samanas, and later when he abandons his wealth, Siddhartha returns to the river. Eventually, as Siddhartha studies the river and comes to recognize it metaphorically for all that it represents about existence and time, he is able to attain enlightenment. Note that the river doesn’t bestow enlightenment in and of itself – it helps direct the thoughts of someone who is ready to listen.