It is significant in Siddhartha that Siddhartha learned from the river and from Vasudeva. This is true because Siddhartha had a very concise goal for the end of his life: peace, enlightenment, and Nirvana. Siddhartha knew that he had to experience his enlightenment first-hand: he would not have been able to attain it via Gotama's teachings. Siddhartha finally reached the peace he so greatly desired from the river and Vasudeva. This was only possible because of the purity of, and indiscernible difference between, Vasudeva and the river on which he lived.
Siddhartha wanted nothing more from life than Nirvana upon death. He was quite aware that he would have to find it for himself and that no one would be able to teach him peace. He immediately recognized the Buddha in a crowd, demonstrating that he was in sync with Gotama. Hesse makes it a point to say, though, "Siddhartha did not reply.
He was not very curious about the teachings. He did not think they would teach him anything new. He, as well as Govinda, had heard the substance of the Buddha's teachings, if only from second and third-hand reports. (Hesse 28)" This shows that Siddhartha knew at an early time that he would not find salvation in Gotama. He later left Govinda in the hands of Gotama and set off on his own.
Vasudeva had met Siddhartha before when he took Siddhartha across the river. Siddhartha went back to that river after his period of corruption and contemplated suicide near it. With time, Siddhartha learned that the river spoke to him. He eventually pondered the workings of the river. "He saw that the water continually flowed and flowed and yet it was always there; it was always the same and yet every moment it was new.