How did the receiver obtain wisdom

Like Jonas, the Receiver was special. He had the ability to give and receive emotions. He is isolated from the superficial society. He is able to contemplate society and understand the dysfunction of the community.

The Receiver already had special knowledge that he didn't know he had. With the memories along with his knowledge, he was able to study all the memories and understand why something was right or wrong. His wisdom came from studying these memories.