Despite spending countless years of his life dedicated to achieving nirvana, Siddhartha had yet to obtain it. Only when he listened to what the river had to say did he reach unity. It had guided him to his goal when word of mouth and countless years of thought had not. Siddhartha had seen how the river could be everywhere at the same time, how its singular voice contained the voices of everything else, and how he must be as unified with everything as the world is.
The river was capable of being everywhere at the same time. This is the first wisdom that Siddhartha had learned from the river. The essence of the river was everywhere at the same time; it was in the air, the mountains, the beginning of the river, and in the ocean where the river flowed. The application of this knowledge that Siddhartha needed to learn was to shatter the illusion that time meant anything and that he is a product of his past, present, and future self. Everything he has done and everything he will do will forever be a part of him, and he should make sure that he never forgets who he once was and that he should learn from his past self.
Soon after Siddhartha had listened to the river speak, he heard that the voice of all living things spoke in its one voice. All of the voices at once are in unity with each other to create the singular sound. By listening to the thousands of voices from the river, Siddhartha learned to listen to all of those voices on his own and that the true understanding of another person only comes when he truly has listened to them. Unity is then found once he is able to understand all those he meets.
The final wisdom that Vasudeva had wanted to teach Siddhartha was that he needed to be in harmony with the whole world in order to be in harmony with himself. All of the voices of the elements of the world together was the stream of events that occurred in life in perfect harmony. At that moment Siddhartha submitted himself to destiny and had realized that the fate of the world goes on, and he needed to accept that. With this he worked towards unanimous goals and was finally in unity with the ever changing world.
Harmony has been achieved within himself, and when he comes across Govinda, he attempts to explain his findings, though Govinda is confused by his examples. It is only when Govinda kisses Siddhartha’s forehead and sees the same qualities of unity that Siddhartha had seen in the river that he begins to understand what Siddhartha had learned. The qualities that the Siddhartha had observed in the river have now appeared in himself. Unity is not something that can be expressed through mouth, but can be shown how something behaves and appears. This is why Siddhartha had not achieved this through the lessons he had heard earlier on in life but was able to learn through the river.