Haha, reminds me of when my ex-quasi-boyfriend was taking abstract algebra in college. I asked him what he was learning in that class, and he said he couldn't explain it. I said, "Oh, come on, I'm a math major too, you can give me *something*. I'm planning on taking it next year." But he couldn't.

The next year, someone asked me what I was learning in abstract algebra, and I realized I couldn't explain it. I never had that experience in any other class, but the operative word here really is "abstract"! By the time you're several months into the class, you're so many layers of abstraction deep that the explanation goes, "In order to have this concept, you need this other concept, and in order for me to explain this other concept, I would first need to explain..." and at that point, you realize the person really didn't sign up for a multi-hour lecture, and then you say, "You'll understand if you take the class." At which point I mentally apologized to my quasi-boyfriend.

But yes, I agree with both your points. Becoming an adult is partially, though not completely, explainable!