When Charlie visits a college economics professor on May 15, what does he discover that disappoints him?

Charlie is disappointed to discover that the economics professor, along with several other professors in different fields, has only a limited, narrow, highly specialized knowledge within his own field.

That is, though this economics professor may have been an expert in interest rates, he knew nothing about military economics and therefore couldn't answer Charlie's questions.

Charlie is practically infuriated, having been very excited beforehand to bounce ideas off someone whom he had assumed would possess...

Charlie is disappointed to discover that the economics professor, along with several other professors in different fields, has only a limited, narrow, highly specialized knowledge within his own field.

That is, though this economics professor may have been an expert in interest rates, he knew nothing about military economics and therefore couldn't answer Charlie's questions.

Charlie is practically infuriated, having been very excited beforehand to bounce ideas off someone whom he had assumed would possess a broad and deep knowledge about the entire field of economics. He was wrong. And his mistake only infuriates Charlie more because it disillusions him: it leads him to the conclusion that Charlie himself was wrong, and naive, to believe that college professors were "intellectual giants."

Like a child or young teenager who is just now realizing that his parents and teachers are humans capable of making mistakes and possessing only imperfect, incomplete knowledge, Charlie is awakening to the realities of the world and to the limitations of his fellow scholars.

Charlie's new powers of emotional insight also lead to a sad discovery in this situation. He realizes that the economics professor, with his narrow scope of knowledge and inflated ego, is afraid of having the rest of the world figure out that he's only human. That's why the professor was so eager to walk away from Charlie after being unable to answer his questions. This professor, along with other men that Charlie used to admire, is now revealed to Charlie as utterly flawed. He can barely handle this disappointment.