Brahman is defined (in some texts) as the supreme self. It is the connecting energy throughout all things. The Native Americans would call it “The Great Spirit” that abides in all living things, but the Hindu belief goes beyond the living to include all things.
In Christian terms, which are sometimes easier for Westerners to understand, the closest thing to “Brahman” would be God, but the Hindu term is far more encompassing; keep that in mind. “Atman” is like the Christian concept of the soul; it is each individual’s part of Brahman.
“How can everything be seen in its true light as a manifestation of Brahman?” Siddhartha accomplishes this by listening to the river. Guided by his guru Vasudeva, the ferryman, Siddhartha listens to the river and gains the necessary insight.
This quote from the chapter “The Ferryman” shows the beginning of this growing understanding. “But out of all the secrets of the river, he saw only one today, and it touched his soul. He saw that this water ran and ran incessantly, and nevertheless was always there at all times, the same and yet new every moment! The one who grasped this and understood this was great!” (39). The parallel here is that Brahman is part of all things. Siddhartha is beginning to see the interconnectedness (or the unity) of all things by listening to the river.
Later on in the same chapter Siddhartha asks his companion about the voices in the river. Vasudeva says, “The voices of all creatures are in its voice.” “And do you know,” continued Siddhartha, “what word it speaks when you succeed in hearing all ten thousand of its voices at once?” Vasudeva's face was smiling happily; he bent over to Siddhartha and spoke the holy “Om” into his ear” (42).
In the next chapter, “Om,” Siddhartha takes the final step in his understanding as his guru Vasudeva leaves him. “Siddhartha stopped fighting his fate this very hour, and he stopped suffering. Blooming on his face was mirth of a knowledge no longer opposed by any will, knowing perfection, and in agreement with the flow of events and the current of life. This mirth was full of sympathy for the pain and pleasure of others; it was devoted to the flow and dedicated to the unity” (52). This quote demonstrates how Siddhartha has finally seen the world as a manifestation of Brahman and as such, he sees the interconnectedness of all things or “the unity.”